I'm sorry for your situation. Other comments have pointed out that legally you don't have to comply with the "no side job" bs, so i agree to keep proceeding with it, and if they try to fire you, bring in the lawyers.

On another note, stories like yours are why I want to watch the entire system burn, using executives as fuel for the fire.

Better to resist and flip the bird to these asshats rather than comply in advance.

Good luck to you, keep fighting, and never give up, if only to spite the bastards