So you are essentially asking people to use your services as a bookie?
I don't know if this is allowed but you can try to see if anyone is interested in doing this but I doubt it because they could just use a vpn or something like this even if they were banned from a site to be able to place their bet.
I am not saying it would work but they were of atleast tried to do it so to see if they were able to get on the site they wish to place a bet on.
Even if they were not able too (from other reasons inwhich I wouldn't even try to consider as being legit) I would beg to say they might as well move on to another site so to put in their wagers.
Because their are alot out there to choose from.