I don't think you understand how soundchecks work.  It wasn't giving an anti fuck -- When you're going thru the motions with your sound team, a singer, esp a hard rock singer, almost NEVER goes all out on the vocals.  There's no need, just cuz its not a performance, you're just checking levels, and you're almost never warmed up beforehand, so you don't wanna blow your voice out.  Rehearsals for a concert, unless you're trying out a song you just wrote/learned, never take place on stage -- it's just a soundcheck.