I do not agree with this in the slightest. As it isn't true in any sense, you can't even say its technically what the person is doing. A vote for a party that isn't likely to win is just a vote for a party that isn't likely to win. The numbers simply isn't high enough for 3rd party to even matter, so no it is not even close to a technical vote for the other side, not to mention it balances out with others from Republican party not voting Trump because he is an idiot.
I hate this argument, because it do not really apply as the 3rd party vote isn't significant enough to say that. If and only if that 3rd party was certain to lose, but had a large base that didn't care about the results would I say you are technically right. Even if this was the case, I would not judge a person by trying to shift blame on them for one party losing because it couldn't get enough voters to go with their policies.
Simply put, the blame can only be put on the party itself for losing. Republican party going in the shit right now isn't because other more conscience Republicans won't vote Trump, it is because they allowed such a candidate to exist in the first place. Same with the Democrats. Let people stand by their principles and stop being so damn judgmental (not aimed at you but others ITT that likes to accuse others of not caring). Sometimes people see standing for their convictions to be incredibly important and it is as that is how change comes about, who are you to tell them what that conviction is worth? who are you to tell them the risks are too high? I am sure we all are aware of the risks when talking about U.S Presidency. There is a difference between full on voting for a regressive asshole and voting another candidate who you favor more over the popular candidate, even if it is just in protest.
I shall vote Hillary, but only because I rather some form of progressive policies in U.S than regressive ones. The risks are high and not just for Blacks and minorities (as many of you keep pointing out), but for poor and middle class whites, the country as a whole, and on the international stage. Anyone accusing people of being a bigot for voting Trump, fair game, but his election isn't only going to damage the status of minorities, but rights for majority of U.S citizens.