I think the idea that it will hurt Democrats is coming desperate Republicans that haven’t caught up with the fact that the Trump Era expanded the base of people that will vote straight D as hard as the ‘conservative base’ votes straight R.
In effect they’re thinking I’m still the person I was in my 20’s- someone who would ‘vote their conscience’ with a third party out of disgust for both parties. Not that I’d have ever voted for RFK Jr’s crazy ass, but third party in general seemed like an option. But Trump helped disabuse many of that notion and made the ‘lesser of two evils’ substantial enough a difference to get through to all but the most hopelessly naive and idealistic.