I got a few hour block from "Spamming" a month or so again. That was about it, I have used it on and off since for quite long periods of time and even had few people "Report for spam" me. I guess Blizzard must get a lot of those and they are not that specific so probably miss them and I guess they don't really care.
But you wouldn't get banned for using SuperGuildInvite it is just an addon, this just automates it. Like I said most you will get is a few hour block, which is nothing, compared to the amount of members you could get.