I wouldn't completely rule out a 4x, it's definitely possible he could have taken this line although it's likely he'd raise the turn. The main question is, is he betting all his draws on the flop? Most villains will just lolcbet but some will just check back because there is a fish in the pot and he won't expect to get a fold often enough on that type of flop.

That said, if you have no further reads, I think calling can't be bad since his line just makes no sense with most value hands.

pre's fine with donk bb, turns bad with your reads, rivers a fold.

Ya, way ahead of is not really the best term. But we are definitely doing fine against his opening range to be flatting here.