I don't feel like they got anywhere close to supporting that thesis in the actual text. It more or less devolves into declaring the show ambitious simply by virtue of it not having a clear roadmap after season one. You only get bonus points for fumbling around in the dark if you do it well.
Whats become clearer in the last few months is that the series does have a reason for going on, because though it may have outlived its best self, it hasnt outlived its moment: At a time when primetime television is choking on gratuitous torture scenesscenes that speak to how much 9/11 and its aftermath are still shaping the cultureHomeland remains the only show thats committed to trying to make sense of that daywhy and how it happened, and what happened in response.
Nothing in this season of Homeland is even pretending to explore "why and how it happened". Absolutely nothing. This season has been actively
disinterested in exploring any form of motivation behind the Langley bombing, and by extension 9/11.
...and what happened in response. The other big criticism thats been made against the show this season is that its conception of international terrorism and the efforts made to combat it is improbable, illogical, and downright ludicrous. To which one might ask, again: Compared to what?
Compared to reality. If the goal is to comment on our national response to 9/11, the response to the Langley bombing has limited relevance. Homeland has spent the season actively avoiding all big picture commentary on how everyone but a couple characters reacted to it. We don't know DC's response, the nation's response or the world's. There is virtually no world outside of the upper echelons of the CIA here. Saul's response is tactical assassinations, and Carrie's response is to care about the safety of her baby daddy.
With Brody's original conflict, we had a window into exactly the kinds of foreign policy that results on terrorist action. They took that and crafted a microcosm to attempt to discuss what it means to play whack-a-mole in the Middle East with cruise missiles and turn a blind eye to the collateral damage. With the show's current conflict, we have no idea why Iran bankrolled the bombing, what their motivation was at the time or currently is in parading Brody around. They're just bad guys. The writers are trying to retroactively attribute a lot of Nazir's philosophy to Iran, but that rings really hollow in a number of ways.
The show has actually devolved into a rather black-and-white look at terrorism. As an audience we may use it to discuss some larger issues, like how much the US and the CIA are willing to compromise in pursuit of 'justice', but the show provides little of that. At most we get Carrie opposing some of these choices, but not on moral or even tactical grounds, only from a concern about whether those choices do or do not help clear Brody's name. Maybe Senator Lockhart gave some opposition, but the show has also made him clearly a dumb, naive antagonist rather than given some of the views he's espoused any serious consideration.
This is a show that no longer has any awareness of or concern with real world geopolitics in either macro or microcosm. Again, this is a show where Iran is parading around the person the world believes bombed the CIA, and all we hear is that the President is somewhat annoyed while Saul shrugs. Homeland at this point is not reflecting on national or personal responses to terrorist events. This is just Saul and Carrie versus big bad Iran. It's not illuminating.