[flopton]

I'd say this is a call if CO is pushing wider than 5%, as he should (and as you have noted).

It is a good play to push over a short stack to isolate and a regular would understand that. Something like the top 15% of hands seems reasonable to do this with.

Edit: I put the hand in from the CO's perspective, and how loose he should push depends on how tight UTG is pushing and how loose the SB will call.

You noted UTG is probably looser than 20% but if SB is loose in this situation as well it might tighten up the CO range.