No, an ex-Bard can be LG. Remember Elan isn't Bard X:
He is Bard X/Dashing Swordmen Y.
He stopped leveling as a bard and is now Prcing into Dashing Swordsmen. once he left Bard he can be whatever alingment he likes.
If he ever want to take another Bard level though; he must be non-lawful. But he has a few level to go before he runs out of the Prc (unless it is a 5 level Prestige Class).