You should pretty much generally be in 3b or fold mode to begin with with 33 in spots like this (usually fold at these stakes because lol at people playing loose in LP at these stakes). When in the SB, it's like especially more likely to be 3b or fold depending on how likely the BB is to squeeze.

If the BB has been defined as a class A squeezing prick, then flatting is just oh so very bad. You could always trap him with like, you know, good hands.