Yes.

Thank you.

The man was not free to marry. Even if the impediment ceases, consent must still persist for the marriage to be convalidated, so it’s not like a bigamous marriage becomes sacramental the moment the previous marriage is declared null. Even though it actually can be convalidated retroactively (I thought it couldn’t but it could, thanks to a certain more informed poster who graciously corrected me and whom I won’t name because he might prefer to stay anonymous), the consent must still persist and consent can’t be supplied by any authority whatsoever. In short, Lexee, because he was marrying you bigamously, there’s the impediment there and if you don’t want to be married to him, he can’t get the marriage with you convalidated against your dissent.
Besides, right now, his first marriage is still assumed valid and the impediment persists (i.e. he’s still not free to marry you now), if you petition for the decree of nullity, it will have to be granted.