Is classic Burzum and Mayhem not well regarded there anymore or something?
Depends. Mayhem is mostly OK because the current band is not espousing racist shite. Burzum always brings out the "I cannot enjoy anything by that man at all". I think the fact he was more a session musician in Mayhem keeps that distance enough for them to be ok with it.
Funny thing is, they will balk and bitch over Peste Noire or some of the more overt bands, and shit like Murduk which is mostly the members rather than the music. But they will still profess a love for Deathspell Omega, even though the singer is an out-and-out racist. The hypocrisy is the annoying part, and least stay consistent in your disapproval if it means that much to you.
They are still fine with Led Zep and shit like that though, you know, Jimmy Page kidnapping and raping a 13 year old girl. Because racism is the worst crime ever, more so than child rape.