On the flop it's possible that someone has a made flush or straight, more likely that someone is drawing, and most likely that no one has a draw.
If we say the SB is calling with 25% [22+,A2s+,K9s+,QTs+,A2o+,KTo+] of his hands and the BB with 35% [22+,A2s+,K2s+,Q8s+,J9s+,A2o+,K5o+,QTo+] (the BB is likely to call wider since he is getting better
pot odds), our equity is ~67% on the flop.
If I tighten it up to SB 15% [33+,A4s+,KTs+,A8o+] and BB 25%, our equity is still ~67%. This is a strange situation where the wider our opponents' pre-flop range is, the less equity we have, because much of our opponents' equity comes from straights that require low cards.
Anyway, we have two opponents, we are solidly ahead of their ranges, and we have a vulnerable hand. I bet the flop, for both value and protection.
In the actual hand hero was doomed to lose his stack whether he bet the flop or not.