If I made a move, then yes, there is no computer task that I know of that would require me to sign on to Brain King and make a move. However, if I clicked the accept link on accident, and I never wanted to play to begin with, I don't see this as a moral issue.

Furthermore, if 2 friends are just practicing openings. Perhaps one is a grandmaster, the other never moved a piece, the beginner would want more time to make moves than say 2 grandmasters. In that case, this would be a perfect solution. You let the beginner practice their openings. After 10 moves, cancel, start over.

There are uses beyond what I see. To prevent people doing this deliberately, you could put in a limitation so that they could only cancel 1 game a day. This would allow those that legitimately don't want to play the ability to cancel and prevent a disruptor from doing it en masse.