The statement is inherently flawed, regardless of its source. Because some exchanges were unaffected does not mean that MtGox was not affected, and the statement itself implies that other exchanges were affected which would be evidence in MtGox' favor.

I'm not saying MtGox was not incredibly incompetent, however nobody is helped by this false defensiveness over a very serious and clear bug in bitcoin that seems to have affected at least a few exchanges.

Regardless of MtGox' incompetence, this IS a serious bug in bitcoin for which a workaround is required, and without which a bitcoin theft is possible.