So there you go. Richard Spencer, according to some the incarnation of Adolf Hitler, Nazi, White Supremacist and Alt-Right racist supremacy, is backing Joe Biden.
Now, does that mean anything? No. Not a thing. If a person who worshipped aardvarks backed Joe Biden it doesn't mean anything about Biden. In a vast country with hundreds of millions of citizens, you're going to have all kinds voting this way and that.
A single person, or even hundreds of people, supporting a national candidate means little. It is only newsworthy because for the last going on four years, the Left - including good New Pro-Life Catholics - made a huge deal about Spencer backing President Trump as some sort of added proof that Trump is not only a Nazi racist, but attracts Nazi racists, and Spencer's support is proof.
Of course I have no doubt that this will be met with those on the Left with all manner of technical exceptions. Or they can just play the Left's favorite 'it's different now' card. Or he can't be supporting Biden for the wrong reasons since Democrats are never wrong. Or they can deny that anyone ever made a big deal about Spencer at all despite all the evidence to the contrary.
In the end, it doesn't really matter to sane people because it shouldn't matter to sane people. To the Left it won't matter because it's no longer convenient to matter.