To be fair, @d00phy did say that

They also started actively working to stop folks jailbreaking. That part, I thought, was too much. Just tell them they void the warranty by jailbreaking and refuse support.

I think it's fair to void support for someone that goes ham in the terminal and breaks a bunch of shit, at least if you explicitly state that doing so will void support. You have root access on your macbook, but I assume the average person using it knows more about what they're doing than the average person jailbreaking their phone (which was pretty much anyone as far as I can remember). Also: If you tell support that you opened the terminal and typed a bunch of stuff and now your macbook is broken, I assume support is likely to tell you "tough luck..."