*sighs* yes, aegon’s claim is actually very valid. he is not some second distant cousin pretender usurper. he is first born son of a king, in a land, where male primogeniture is an actual legal thing.
“viserys, the king, named rhaenyra an heir. not aegon.” - well, that’s nice and all but did he legally changed the primogeniture? did he made an actual law that woman when elder was to inherit instead of their younger male counterpart? no, he didn’t because that would challenge his own position. that’s the joke. viserys wanted rhaenyra to be the queen, which is totally fair and reasonable, but he was too comfortable to take the kingship from rhaenys.
viserys wasn’t some kind of progressive feminist king - he just had favorite child. and aegon, while ill-fitted to be the king, had a good claim. if viserys wasn’t the blind fool he was, he would realized that but he didn’t. that’s all.