How often he gets paid and whether he has a schedule set doesn't enter into the "is he a partner or employee" evaluation as it does for the "contrcxtor vs. employee" one.
The question is his financial relationship to the partnership. If he is granted a capital share (more than 1%) or he gets paid as a precentage of the profits, then he can be a partner.
What they're likely "getting at" is not having to pay all the employer stuff (their part of the FICA nor provide any benefits).