My understanding of the rule (having no "capologist" credentials) is that an U22 can be paid $200k above the max (so, he can be paid $812k) and regardless, his cap hit will only be $200k. Furthermore, there is no allowable application of xAM to either reduce the $200k to the minimum $150k, nor to pay him more than $812k.
As such, my guess is he is being paid $812k, his cap hit is $200k, and we still have all our xAM.
Obviously MLSE doesn't care about the actual cash wages they pay (which is ideal for supporters), they care about managing/optimizing cap space.
So, this signing strikes me as really smart and a great use of the U22 slot. I would think the only criticism could be in the form of there being a better player than Ayo available for the slot. Of that I have no idea. But for sure he has a good agent, and for sure he would have had options. So I don't believe TFC was ever looking at being able to sign him for less than the U22 max of $812k. In the absence of a better player, this looks pretty good.
So net net, I love the deal. A bird in the hand....