I think villain's range is capped to either air or a big hand. If it's a competent player that you're up against, and understands generalized 3-bet tendencies, they are likely putting you on AK with your pre-flop 3bet and can probably get you to fold on a draw heavy board. They probably had some pocket pair, even as low as 8's.
If it's an ABC player, they most likely just hit their draw and had QJ. It's up to you to decide which of these players it is. You took the safer route.
FWIW, on draw heavy boards on the turn, after villain check-called you on the flop and then checked again, I'm checking behind almost 100% of the time to see what they do on the river and evaluate from there. It's amazing how often players check the nuts with the intention of check-raising, whether it's on the turn or especially on the river. People lose so much potential value in those spots. It's as if they think it's still 2007 where slowplaying a big hand is +EV (of course to balance my range, I'll do that some of the time
).