A ball that didnt' stay down, is not considered to be pocketed by the rules.
I'm all for sportsmanship in the game. However, I dont' feel this is open for negotiation. The most important thing to do is to shame the manufacturer or even better, shun them, until this problem with the pocket is fixed. This is a flawed product that has no business being used in a serious tournament, like those crappy balls that rolled off or a table that is significantly off level.
I've done this thing myself in snooker matches, it's far more likely in the side pockets. Hitting the ball hard and square into the pocket can cause it to jump out. Nobody offered to give me those balls, nor would I expect them to. If offered, I wouldn't accept it. In snooker it's part of the game because the conservative brits won't accept anyone to tamper with their "perfect" game. While they may be a bit too conservative for my taste, they did manage to save their game from the crap that pool had to go through, so maybe they are right about this.
In US pool it's a little bit different, because it is not commonly expected to occur with professional style tables (but home tables with leather pockets, you should expect this), though knowledgable players are aware of the risk. I still think the rules stance on this is the correct one. The pros will know about this problem after a short while, and adjust their games. However, hopefully the tables are fixed promptly.