Mt. Gox's explanation does not hold up to close scrutiny. They could fix this issue by confirming transaction inputs, outputs and amount instead of just watching the hash.

When the official explanation doesn't make sense, you must ask if there is another explanation that makes more sense. Who benefits from their actions and statements?

A lower price would presumably benefit Mt. Gox if they've been scammed out of Bitcoin and don't own enough to fill withdrawal requests.

Since Mt. Gox has been unwilling to prove how much Bitcoin they own, it seems like Occam's razor may be more appropriate here.