UTG+1 limps, that for me can be any pair at this level, I'm limping 22 UTG all day at 2nl, I imagine 4nl is not much different. It could even be unsuited braodway, so I thought my UTG+1 range was actually too tight!
And again, at 2nl I expect someone making up the blind to be calling any two, I've even seen people making up the small blind with like 83o after it's folded round to them.
The only info I have from the limps is they don't have like AQ+ QQ+, but even then, I've seen people limp monsters in early pos at low levels quite often. Personally I can't begin to narrow their range to one that truly threatens our hand until after our raise on the flop, at which point I'm thinking we're in terrible shape. I don't mind the raise on the flop if we use the info that the others give us after, it seems better than calling hoping to hit one of four outs, or calling two people down to showdown hoping that bottom 2pr is good in a monster limp pot.
I must be honest, I would probably go with it if this were a heads-up pot, especially if we have pos, ie UTG+1 folds to our raise, I could consider then that SB can be raising Kx, Ax clubs or Jx, but I would certainly be aware of the dangers of doing so with someone we have only 6 hands on.

I hope our hero here made plenty of notes when he saw the showdown.