A 15% PFR
I dont think that this is relevant.
and a 5% 3-bet is übertight.
yes, in my first comment I said that this is the only bad thing I see against shove, that a 3bettor who is tighter 3betting is likely also 4betting tighter.
Naturally he is tighter from UTG than from the button.
Like most of regs, still this is not relevant.
The caller (OP) should have a tight range calling in HJ and squeezer (which I admit is loose) is or is not going to observe this depending on how good he is
UTG also open raised 2bb which gives better pot odds for MP to call looser than standard, giving CO more FE. Most of regs when using 2bb open raise from UTG do it with a wider range than 3bb (mostly when a fish is in blinds).
If you are overoptimistic, then you peg UTG as loose in this particular situation. I m o, there is no ground for that. It is just wishful thinking
You dont need UTG to fold that often in order to make a shove +EV with so much dead money. If you see the 4bet of UTG value heavy, he can also see your shove very strong and he could be folding AK, QQ together with bluffs, giving you enough FE.
I am not saying that a shove is super +EV, but I think that it higher than 0.
UTG may want to bluff, but he is really thinking "I can't wait 'til I get AA and can bust this maniac", not "I think I'll start 4-bet bluffing here and now".
this is all based on assumptions. If your assumption is that utg is bluffing often enough then we shove otherwise fold. It is also a very rare spot, so it can't be estimated with population stats. So there are left only intuition and experience.