If you take a look at the back of any Deathlike Silence record, you'll notice the words "anti-mosh" and a string of numbers that refers to each and every individual record that the label has released. For example, Deathcrush is anti-mosh 003, and De Mysteriis Dom Sathanas is anti-mosh 006. The reason why Euronymous used "anti-mosh" is because he was against moshing, possibly because it was fun. You can see it in the logo of his label too, it says "no mosh, no core, no fun, no trends" i hope this clears it up.
Euronymous Being Questioned by Journalists in 1993
I apologize for the quality being so low, i couldn't find a better version. This was after Euronymous closed down Helvete and Varg ended up in jail for telling exaggerated stories to a journalist about the Black Metal scene.
Translation:
Øystein: We know absolutely nothing.
Interviewer: We haven't even asked what this is about yet.
Øystein: They gave a call to (inaudible).