Ghostrider0002

The Tyrells do not hold the influence that House Tyrell had in GOT; at this time, they are merely a house elevated by House Targaryen just a century ago, whereas most of the great houses of the Reach have histories spanning several thousand years. Before the Conquest, the Tyrells were merely stewards to the Kings of the Reach from House Gardener.

I think he doesn't know it himself yet, but he's got it in him to take whatever he can get while he can.

Yes Arnold is his front man

I don’t quite agree with you on this point because, while Aemon might not fight purely for vengeance, he would see a potential gain and be tempted to marry Rhaenyra, eliminating any potential competition in one move. (However, he has already refused Rhaenyra before for many reasons that are still valid.) Another point is that Aemon and Alicent are not in each other’s minds, so they don’t know what you know—neither of them truly knows the other’s intentions or limits.