I might be rly wrong about this, but i'll give it a go - if anyone sees this as wrong please correct me because maths is not my native language.
so from what i understand, the EV of 4betting (and calling a shove) with AK is as follows:
EV(4bet) = P(fold)*(amount_won) + (P(jams) * EV | jams)
so first we find EV | jams (the EV, given that villain jams), which is when we call against his jamming range.
if we open in CO to 3bb, BU 3bets to 9bb and we 4bet to 22.5bb, and villain 3bets 5% in total, jamming with QQ+ and AK (i.e. 2.6%), thus folding 48% of his 3betting range to our 4bet.
EV | jams = (P(win) * (amount_won)) - (P(lose) * (amount_lost))
EV | jams = (0.395 * 124) - (0.605 * 77.5)
EV | jams = 2.0925
so...
EV(4betting) = 0.48 * 13.5 + (0.52 * 2.0925)
EV(4betting) = 7.5681
so by 4betting with AK you expect to make ~7.6bb each time against someone with that range.
against someone with no folds to our 4bet, if his range is QQ+ and AK, our EV is...
EV(4bet&call) = (0.395 * 124) - (0.605 * 77.5)
EV(4bet&call) = 2.0925
so we expect to make roughly 2.1bb each time against someone with a 3betting range of 2.6% and no FE with our 4bet. just because that's +EV, it doesn't mean calling the 3bet OOP isn't more +EV, for example.
i really hope i did this correctly - it looks about right. so yeah, it's a marginally profitable call after we 4bet because we only ever have 39.5% equity in the hand, but it is still +EV. would be pretty damn difficult to calculate the EV of calling and playing OOP, but it is never gonna be a bad play to play this way.