A check/raise from blinds is typically very strong. From the sizing, a good player will do this with a vulnerable 2 pair but I would exclude a flopped straight in his range unless there is a FD on the flop. He may raise a straight here but it will likely be much smaller in $. I would make the same assumption about a set. You will see recreational players check/jamming here at small stakes because they don’t want to feel the pain of a 2 outer but those are usually easy to spot. An advanced player might make this move with 86 but it is a bit optimistic. Based on his sizing, I would narrow his range to 2 pairs and pair plus SD which has QQ crushed. It seems like a pretty easy laydown IMO.