I know Richard has his spergy moments like
this, talking about wanting the US Military to enslave Haitians, and also the infamous Milo leak from last year, but I think it's because Richard is a lot more eloquent when he speaks and tweets in general. I don't know Richard too much but I did hear his bit where he talked to Catboykami and to me he came off as much more reserved and pretty quant in his words. If in an alternate world where Nick would be against Catboykami, I'm pretty sure Nick would definitely place an insult there and there.
Of course that's Spencer up against a druggy trap fucker but still.
And I did listen to one of David Duke's podcasts before, his 'Aloha American' episodes in full and again David Duke has this combination that Spencer has that is probably why their accounts are still afloat, glowie speculation aside.
Unlike Nick: They're not so overly aggressive nor as crass as him in terms of words on the regular. Plus there's also the fact that those two are already well-known names to normies.
David Duke is well known to boomers and older people I bet, and he's even been featured (not himself, a character based on him) in various media and movies IIRC, I think it was BlackKKKlansman or something. While Richard is infamous for that guy who got punched and organized Charlottesville, Milo leak, and many more.
Nick is viewed as a growing figure that's probably why Twitter went extra on him.