Quote from Lucrum:
Like I said, I made no alterations. I merely lopped off the beginning and end.
It's done all day every day without complaint by anyone I've noticed. Often for the sake of brevity or to focus on only the portion of a post that's actually being responded to.
The prohibited "alterations" you're referring to would be, for example, something like:
THAT WOULD be the kind of alteration that Magna has a bug up his butt over. Which I don't do anymore since the practice was poo pooed on by said moderator.