I'd suggest the house-rule that the minimum 1 thing only applies if the ability score was not already less than 1 before the penalty was applied. Much like the bucket of water trick, Wizards clearly didn't consider all the corner cases.
While we're on the subject of silly things, it would seem silly to me if a creature with strength 12 and a -6 penalty to strength is rendered helpless by ray of enfeeblement, but a creature with strength 6 and no penalty is not.