You seem to have gotten the things right.
Like, how do you determine how many posts/replies a person has made on a specific topic?
My guess is that they are not interested in such metrics.
If they don't want posts in certain areas they just don't pay for those posts. For example some may rule out local boards, or even the altcoins area.
Also, if the said project is not planning to utilize an escrow account, well maybe cause they have trust issues for the market, would that be detrimental? give off the wrong image to the potential legendary/hero signature-bearers? Would it be bad enough that the team may have to reconsider their choices and make the said escrow thingi? A general direction to creating the said account would be also very helpful.
Especially at the campaign start, either a trusted campaign manager, either an escrow for funds would be needed. In many cases the campaign manager also keeps some funds.
If this condition is not met, there can be a trust issue and especially higher rank users may not be interested to join that certain signature campaign.
About "reconsidering", well, I am sure that if the campaign manager is less known and there's no escrow, some people will start asking about it as soon as the campaign is posted.
Lower ranks are less careful and may hurry to jump in.