You know, I've changed my opinion since my initial reaction after thinking more. Teddy Roosevelt getting shot in 1912 didn't get him a third term. I'm not sure how much independents and undecided will be swayed.
If a party can’t get its voters to come out - especially reluctant voters, that can make a big difference. If you are a Democrat but aren’t that keen on Biden and you think he’ll win your area anyway, you might lot bother with the half hour trip, and that might swing the election.