I'm not so sure.

With only 550 blocks stored, how can/would a pruned node make sure that an input given by user to be signed in a block isn't a double spend? There'd be no way to check that on such a node, right?
(E: Although i think there's probably a mechanism for this, otherwise it wouldn't be able to verify any transactions at all.)

finding a valid nonce would probably be possible on  a pruned node, but i could see some problems with the construction of a valid block.