Because it goes against groupthink. It implies that the Army might be there.
Nothing wrong with his statement. Something wrong with his boss who will take retribution upon him for making that statement.
Who cares about supposed “groupthink”?
See Marine_Uncle’s thoughts below. It would be the height of irresponsibility to automatically plan for a withdrawal because the chosen one stated a date.
We should leave Iraq in an orderly withdrawal commensurate with the ability of the Iraqi government to assume control of their country.