well, we need 33% on the call here, (41.5% to stack off)
let's say he sqz prflop is 4% ($3b4o)
I'd exlude this from his flop range (as he checked) : KK!cc,AA:cc,AA:35
OTT, he should be shoving something like this: AA: (3,5,Q,T,K,9J,J),KT+,K:cc,K:hh,T
QJ+,Qcc+,Qhh+), Q9K: (cc,hh)
so we have 35% here, looks break even call to me, if he's more likely to make mistacked with SPR 0.45 OTR, than you, then calling and playing river depending on the card (calling any flush and straight or shoving them yourself) seems like right play.
but maybe, my turn delayed Cbet range is too ambitious