If in fact a player knowingly prolongs a game out of spite, that is unacceptable. Did he chat at all during this period? In any event, it would be uncharacteristic for him to pull such a stunt, but it's hard to chastise someone for one incident. If it turns out to be a pattern, then folks might consider not putting him in games. But everyone has "off" episodes, and if someone gives assurances they "won't do it again", I would give them a pass (at least until they do it again).
My guess it was isolated situation. Ask him about it, or get a response from him before out and out labeling him a griefer.