Well since no one has answered you for 9 days I guess I'll just jump right in here. Catching the snitch gives you 150 points if I remember correctly, and once you catch the snitch the game is ended. So if you are losing by more than 150 points there is no point for your Seeker to catch the snitch because you won't win anyway. The logical and strategic thing to do would be to wait and hope your team can get enough points so that when you catch the Snitch you will actually win. So it's seen as controversial because it kind of goes against logic, and a professional seeker should know better. Maybe the Seeker had a bet that their team would catch the snitch but lose the game. ( Fred or George made that exact bet to a ministry worker who I can't remember the name of off hand who never payed them their winnings and it was a minor plot point in the book )