I doubt you'll get unbanned but I do hope the game has an appeal process for beta-testing bans by the time the game moves out of beta - who knows what kind of bugs could cause a false positive.
Having said that I believe the community at large is reaping benefits of the somewhat strict system...
Bumping this thread, I experienced the same issue.
I accidentally clicked the "Hero Sandbox" button while looking at a Hero in the "Heroes" menu right as a match was loading. This immediately put me in the hero sandbox. I left the hero sandbox immediately, but didn't see an option to rejoin the...
