People need to understand that nothing is forever and it is 1000% the right thing for Kyle Gass and Tenacious D to just lay low for a while.
They fucked up big time (debate this if you want but I won't) and now they just need to disappear for some indeterminate-as-of-now period of time.
This is not forever and it's not unrecoverable -- it's minor as far as "I said something bad and fucked my career" scandals go. In ~12 months Gass will put out a longer, more in-depth apology. Black will re-embrace him when then heat dies down and talk about how much his friend learned from this experience, and they will inch their way back to their previous status quo.