However, another thing a co-op could do is allocate work among members who do the same kind of work while respecting limits on how much work each member is capable of doing. I assume the rule's purpose is roughly, "Your benefit is predicated on you being incapable of working enough to support yourself, so if you prove otherwise, we can't give you the benefit." Limiting how much each person works seems compatible with that.
But I'd guess the work would need to be allocated based on members' actual capability, not the monthly dollar limit. If someone's work adds up to just barely under the dollar limit consistently month after month, it strongly suggests they're capable of more. Even more so if lots of co-op members have that pattern.
Such a co-op could serve a legitimate purpose because people who can only do limited part-time work may not have much opportunity. Many employers want someone who is full time. Also, some disabilities may make it where someone can only work sporadically. So the co-op could enable someone who is capable of (say) 10 hours/week to do that instead of 0 hours/week.