Comment Re:Advice : do it from home exclusively. (Score 2) 353
That depends on what state he lives in. Several states (e.g., Kansas, among others) have laws which state that work done on your own time with your own resources is yours, and any contract clauses which state otherwise are null and void.
As always, OP should consult a lawyer, as even if such a law exists in his state, there may be finer details which could still prevent him from developing his plug-ins.