You're absolutely right to doubt the effectiveness of consequences" when he's tired and scared.
I guess I would keep reassuring him that he's safe, and you'll help him if he needs to go potty or wets his bed. Maybe even the fact that you had to change his whole bed got him shook up about the whole experience, so tell him you're sorry if that scared him. When our son wets his bed, we actually put an old towel on the wet spot and deal with changing the bed in the morning, so as not to disturb his twin sister, who's pretty much done with bedwetting.
Then again, you could offer to let him sleep with you when he wakes up, if that works for you. Or, move the baby to your bedroom? Maybe the baby's presence disturbs him, maybe it was stressful to hear the baby crying the night he wet his bed, and he remembers that?
Fear is huge for little kids, so he needs you to be his safe haven. Good luck.