I understand the concern that people have that Trump sucks and Biden is... uninspiring.
Badgering Shaun into casting a "hypothetical vote" for Biden isn't going to fix this problem- in fact it will only further piss off leftists who don't need more pissing off right now. https://twitter.com/shaun_vids/status/1252805155231109123

Biden was not chosen with leftists in mind, and he is a tough pill to swallow for us (for those choosing to swallow and not spit).
There's no amount of Youtubers blowing smoke up our asses that will make that better. And leftists are not necessarily like other groups-

I don't say that as a brag, but anyone who has been to a meeting of leftists knows that "going along to get along" is not a thing.
Neither is blindly following authority or media figures.

If you want to make Biden more electable among leftists, try to convince him to go with more leftist policies. Apply pressure.
Making him a slightly less obnoxious choice would help a lot.