That is basically the only way a death penalty supporter can justify their stance. It does not deter crime, and a large number of people on death row are innocent. It's also significantly more expensive, sometimes bankrupting small towns. So in order to satisfy their bloodlust for something that does not even function in society in any way, they must be willing to kill innocent people and cause society extreme financial harm as well all for a result which doesn't even scare criminals into not committing crimes.
There is no actual way around this argument: they either are OK with those downsides in order to see someone they dislike die, or they are not and understand why the death penalty should never be a thing.
No, it is not the only way a death penalty supporter can justify supporting the death penalty. You say the death penalty doesn't deter crime, but some studies have
found otherwise, and on balance the studies appear to
be inconclusive (notwithstanding Politifact's partisan-motivated "Mostly False" rating). A person can rationally believe that the death penalty
might deter crime, and the evidence, on balance, would not refute that belief.
In addition, some death penalty supporters don't rely on the deterrent effect at all in making their case. Professor Robert Blecker of New York Law School, for instance, makes his case
on the basis of retribution--the death penalty is a punishment fit to some crimes.
The other issues you raise either are not necessary characteristics of the death penalty or are the subject of reasonable disagreement. Blecker suggests a higher standard of proof (higher than "beyond a reasonable doubt") for imposing the death penalty, for instance, which would reduce the number of innocents sentenced to death. The costs of prosecuting a death penalty case don't need to fall on small towns that can't afford it--the state can bear those costs instead, for example. And some may reasonably weigh the benefits of imposing the death penalty as greater than the detriment of having to bear high monetary costs; that is not a question subject to empirical determination.
You can reject all of the above arguments, of course, but it's dishonest for you to assume that everyone must agree with your misreading of the evidence and weighting of the moral issues involved.
*****
On topic, this has been an interesting case to watch develop. Things started getting interesting in March 2014, when the Supreme Court of Oklahoma asked the Court of Criminal Appeals of Oklahoma to issue a stay of execution for Clayton Lockett. (Oklahoma has two high courts. The Supreme Court considers appeals in civil lawsuits, while the Court of Criminal Appeals considers criminal appeals. If memory serves, Texas is the only other state that has this bifurcated system.) The CCA refused, finding that it had no jurisdiction to issue a stay. After a
few back-and-forth orders from the Supreme Court and CCA, the Supreme Court eventually issued a stay itself, even though it had always rejected having such a power in the past. Governor Fallin refused to recognize the Supreme Court's order, but issued an executive order delaying the execution anyway. In the end, the OK Supreme Court rejected Lockett's lawsuit, and he was executed on April 29, 2014.
But:
The execution of convicted killer Clayton Lockett was botched tonight at the Oklahoma State Penitentiary before he died of a massive heart attack. The event prompted officials to postpone a second execution scheduled for two hours later.
Lockett was given execution drugs and reacted violently, kicking and grimacing while lifting his head off the gurney to which he was strapped. He was pronounced dead at 7:06 p.m. -- 43 minutes after the process began
After the botched execution, Charles Warner--who was scheduled to be executed the same day as Lockett, but whose execution was stayed while Oklahoma investigated what went wrong--filed a federal lawsuit along with 20 other Oklahoma death row inmates, alleging that the drugs used by Oklahoma violated the 8th Amendment prohibition on cruel and unusual punishment. Four of those inmates--including Warner and Glossip, who is the subject of this thread--moved for a preliminary injunction. That went all the way to the Supreme Court of the United States, which
initially rejected (PDF) their application for stay of execution. Warner was
executed on January 16 of this year. CNN reported that, during the execution, he was heard to say, "My body is on fire." Otherwise, he "did not appear to be suffering and did not show any obvious signs of distress."
Following Warner's execution, the U.S. Supreme Court voted to grant
certiorari in the case, with Glossip as the named petitioner. At that point, the Court had still not granted the application for a stay of execution. As the New York Times explained, "There are nine justices on the Supreme Court. It takes four votes to hear a case, but it takes five to stay an execution. That can leave a lethal gap." It turns out
it's customary in cases where
cert. has been granted in death penalty cases by the vote of four justices for a fifth justice to vote with the other four to stay the execution. That happened in
Glossip the week following the Supreme Court's grant of
cert. (In the meantime, even the state of Oklahoma asked the Court to delay the executions, but only with respect to the existing three-drug protocol that were being challenged (the one that had resulted in Lockett's botched execution).)
Glossip
lost in the Supreme Court (PDF) in late June, which brings us basically up to date with the news in the OP. The CCA's stay is just the latest in a long train of twists and turns over the last two years.