Since Quidditch players are allowed wands, as evidenced when Harry used the Patronus Charm in Prisoner of Azkaban to fend off 100+ dementors, does that imply that they can use Accio to summon the Snitch? Or did Dumbledore or Madam Hooch see this problem through and placed the Snitch under an Anti-Theft Charm so as to prevent the capturing of the Snitch so easily?
The rules of Quidditch clearly state that wanded magic must not be used on the balls.
Players may take their wands onto the pitch, but they must not be used on or against any players, any players' broomsticks, the referee, any of the four balls, or the spectators.
Given the temptation to cheat and the trivial ease with which an "anti-accio" spell can be cast, it's reasonable to assume that the Snitch is also proofed against simple summoning charms, even if it wasn't already an immediate forfeit to cheat by summoning it.