I would report it to the Tour Director. They do track issues with TDs and that will be happening more often as it relates to TDs getting to host an event or that high of a tier the following year. I would say this that if there are only 3 pros, that's less players than what the TD would be required to host a division. I could see a TD having grounds to withhold added cash in that scenario. On the other hand, if the TD has actually raised the $500 from sponsors, he would have cash in hand that sponsors would in theory expect to be going to the pros how ever many showed up.
Since cash can only be paid to pros, it's pretty clear that "added cash" means cash added to the pro purse because CTP and skins money doesn't count in payout. The only thing the guidelines don't indicate is how it's distributed among pro divisions.
Rater of the tossed arc.