It's not a must that the participants must post there. If the campaign rules were saying "you must post in thread x and X or else you won't be paid" then that would be considered a push to make participants bump the thread.
I don't see any problem with CryptopreneurBrainboss' request
I have to agree. That is a simply summary and explanation regarding the situation.
Can this be considered as "Paid Bumps"?
Paid Bump is not allowed by the forum policy. It may result to permanently ban all users engaged including the campaign manager responsible.
It cant be considered as paid bump as the campaign manager has not offered any payment for posting on the announcement thread. Everyone can say to visit his website or something if they like. If the campaign manager told you must have to post on the announcement thread or the campaign manager told there will be no payment if not posted on the announcement thread then we could say paid bump and the campaign manager could be accused.
For campaign managers it can be on occasion a difficult line between promoting the brand and posting in the thread that promotes the brand. In any campaign by any campaign manager if there was a quota to bump any thread or something like that then issues of paid bumps could be discussed but as you rightly said there is nothing like that going on here.