So they mainly want attention. Seems like the answer is obvious then, deal with them the way you would deal with an actual 12 year old that wants attention. Ignore them.

No matter how they spin it, if the Pope takes their offer, they paid him off. It doesn't matter if it goes to charity, they used money to coerce an action from him on a specific day in the hopes of manipulating his followers. At best they're trying to make the Pope jump through hoops for them. At worst they want to say "Jump!" and have him ask "How high?"

They're moneylenders trying to exploit a loophole by staying outside of the temple and calling it 'a donation'. It's disgusting, it's pathetic and they should be ashamed of themselves.