"They spoil everything. We are supposed to be a buffet, but they eat everything out of the bowls before people can get there. We just can’t keep doing this."
This is the clue, I am going to guess they turn up early before everyone else, eat everything on the buffet and just keep eating whatever is put out. Plus knowing your average rugby player they will be aggressive, rude and be self important.
The owner has put up with it for two years to be fair, with them making no effort to buy anything else, etc, I suspect it has as much to do with the fact that other people couldnt eat/get to the buffet and were put off by these two, than them actually eating the food.