This is clearly fake. If it had really happened at least one person would have called them a slur and downvoted their entire post history, then they would have been permabanned from 7 different subreddits.
Now-now it's Reddit - he might have posted on one of the subs that people monitor with bots and silently autoban you from other subs for having ever participated in the offending sub. So he might very well have been Perma banned from 7 other subs for the comment, whether it was up voted, downvoted or totally ignored.