He could change his TN to a Management Consultant but that would mean entering into a consulting agreement with his current employer (assuming that he also wants to keep this employment).
In this case, wouldn't his new management consultant TN be tied to his (now former) employer, so would such revenues from his side projects need to flow through the TN sponsoring company in order not to step outside of the terms of his TN?
Side question: what are the risks of a TN holder operating what looks like commercial side projects whether they generate revenue or not (eg publishing a mobile game or running a successful website unrelated to the TN they hold - is it still commercial activity, is it still seen as removing a job from the US labor pool, etc?)