If this is an actual employment relationship (not an independent contractor relationship) then the employer is doing everything wrong -- the employee needs to make a wage complaint with the state, and the non-compete is worth less than the paper upon which it is written.

If this is an independent contractor relationship, there is a question of whether the person is properly characterized as an independent contractor, and the worker may want to have that relationship reviewed by the state department of revenue or IRS. However, if he is properly classified or wants to try to recover the money before the evaluation is complete, he should sue in small claims court. The non-compete, being signed after the alleged breach, is irrelevant -- you can't violate an agreement you have not yet accepted.