Hypothetical Hand - Crappy Draw to SB C/R

[Unarmed]

5/10 - 100bb stacks
Raise 4 [img]/images/graemlins/heart.gif[/img]3 [img]/images/graemlins/heart.gif[/img] Button, SB calls.
Flop K [img]/images/graemlins/heart.gif[/img]Q [img]/images/graemlins/heart.gif[/img]5 [img]/images/graemlins/club.gif[/img], ($70)
SB C/R's 50 c-bet to 150.

He doesn't do this without a FD, set, or two-pair.
He will fire two more shells with his full range if the flush misses.
I'm not sure how he'll react if the flush hits the turn or river.
Is this an auto-call? Is it a call if he reraises KQ pre?