Re: the aftermath of Viserys I’s death in the absence of a male heir, sure, the Greens could make any number of arguments. The question is why anyone but the Hightowers would care. Rhaenyra vs. Aegon II is a legitimately confusing succession issue on which reasonable people could and did disagree. Rhaenyra vs. a younger daughter of Viserys I really is not. It’s like Mary I vs. Lady Jane Grey. Rhaenyra will win easily.

To continue my previous point, you seem to be assuming that succession disputes are simply about politics, and that the quality of the alternative claimant’s argument doesn’t matter. But of course it does! There’s numerous examples of claimants representing a theoretically dominant faction losing because they had a shitty case – beyond Jane Grey, I’m thinking of the Duke of Monmouth and the Catholic League in the French Wars of Religion. Having a good hereditary claim actually matters.

Well, you have the Hightowers, the Lannisters, the Strongs, the Redwynes, the Baratheons, etc. They’re all on board. Also, anyone who doesn’t like Daemon Targaryen, and there’s a lot of those people running around because that man mass produces enemies. And of course, whichever prominent lord Aegonrya was married to. 

Of course the quality of the argument matters, but it depends on how people see the situation. If we’re going by legal claim, a lot of lords might say that after the Council of 101 neither Rhaenrya nor Aegonrya could inherit, so the nearest male relative of the Targaryens should inherit.