That is a different argument. Aldo was using IV bags to recover pre-USADA. If he is a true 145, why did he need all those IV bags, and why has his ability to fight for more than 3 rounds deteriorated? (the same thing is happening with Chris Weidman, Johny Hemdricks and many more)
Conor fought at 145, became champion. Moved up to 155, became champion. Moved to the UFC, became champion at 145. Then he moved up to 170, and he is 1-1. Then he came down to 155, and became champion. Went to a different sport, and did OK (depending on how one feels).
Based on this evidence, we can reasonably say that if it was possible for Conor to maintain his athletic ability while moving up to 185 or 205 or 265, on any given fight night, he could beat who ever is the champion in those divisions and become champion.
Conor is a true P4P fighter. I am not the biggest Conor fan. But, I go with logic and evidence, the evidence shows that the guy can fight at reasonably higher weight classes.
TJ going down to 125, is weak evidence for his claim to P4P. If he moved up a weight class, like Conor has done, then he would have a more legitimate claim.
P4P is for fighters who move up, and not down.