It’s all word play, total information control and fog of war; by not attacking Putin directly, they avoid upsetting the Russians that still have total confidence in Putin and maintain that possibility that Wagner could still end up in alliance with Putin anyway, like with Chechens.

Attacking the military talking-heads however, doesn’t risk anything, most Russians don’t really trust the entire regime anyway, just Putin.

Once Wagner have more and more control of Russia, they can just go after Putin.

This is all speculation on my part tho.