I just don't understand what's the problem is? any campaign will trying to find the best poster who agree with their pay rate or private agreement, if not they will look into other user, not only ex-Chipmixer participants. They're allowed to join any campaign, similar like many users in this forum where jump into other campaign with better pay rate, rule or project they will promoting.
Do you think this will lead some people to try to build up an alt account so that in the future they can get paid for two campaigns for a total of 50 posts per week?
Any user can create alt account to join a signature campaign, not only ex-Chipmixer participants.
to roll back their habbit of hitting 50 posts per week instead of signing up for alts.
I don't think it's correct to say their habit is to hit 50 posts per week, some participants doesn't always create 50 posts and some participants also post more than 50 posts per week.