Bannon would had been quicker to point out mail in ballots/maillot harvesting. But the question is would Bannon had been able to do anything about it? Or would the outcome be the same anyway because it's up to each state on how to conduct their election.
Outcome very well could have been the same..but I do think the pressure would have been different as would a more prompt response with legal challenges.
It is entirely possible that Kushner wanted a better legal ground game but got overruled to save money.