Your argument is certainly valid, but if he approaches it like a job and already has the skill he needs it will just be a $20 extra on top. Even if he is feeling tired ect. all he has to do is play on auto-pilot and expect to break-even during this poor level of play. (he still is making that $20 per hour) and he won't have any problems.
If your going to try to play poker professionally at the low stake level this is really the only way to do it. Doing it without the $20 per hour on top and you will literally want to kill yourself. So if he is set on playing professionally with his current BR this is the best option.
GivemeaBJ, im not knocking you, you have some good points and it would probably be better for his game in the long run to only play when he feels like it, so that may be the better option if he one day wants to crush the 10/20+ games!