(*semi-bluffing here isn't necessarily a mistake for the villain- but he'd rather take a free card than end up being c/r all-in)
True of course - but also therefore the fact that he bets the turn in position rather than taking the free card probably skews his range towards the stronger side - ie made hand and pair + nut flush draw. Difficult to say by how much this alters his range given that he's an unknown, but I wonder if you shouldn't make it your default assumption that he'd usually check behind with the Q or K-high flush draw.