That statement belongs in the category 'so general it hardly makes sense'. The median Trump or Biden supporter certainly doesn't, whereas it's easy to find at least one that does (making such a statement untrue in binary logic). If I'm making a particular vote I would obviously hate to be associated with whatever nutcases decide to make the same vote, so I can understand the urge.
Either way, the direct issue is Trump's non-denouncements of violent supporters at occasions where it would have been expected, not whom such supporters decide to support