While technically speaking he wouldn't get anti-Hillary votes, he could easily get Anti-Biden votes. Actually, he could get more, because Biden seems less popular than Hillary, at least in terms of approval polling.
If we try to compare Hillary's approval ratings at the same time in the election cycle in 2016 as right now, in January of 2016, Hillary's approval polling was around 43% favorable, 51% unfavorable. At the time of the election itself, it had gotten slightly worse, as she held a 42% favorable, 54% unfavorable (
Source) Biden right now is at 39% favorable, 56% unfavorable. (
Source) These numbers indicate there is actually stronger Anti-Biden sentiment right now than there was Anti-Hillary at the same time in the election cycle!
For comparison, Trump was at 42% favorable, 49% unfavorable in late January 2016 (
source), and is now at 43% favorable, 52% unfavorable (
source).
So, sure, he won't get Anti-Hillary votes. But that doesn't mean that much, because his opponent is (presumably) Biden, and people right now like Biden even less than they liked Hillary during the 2016 election, at least based on the polling.