I’m so sorry to hear about your friend’s false permanent ban. Seconding everyone above, there is currently a oversight with the Defense Matrix anti-cheat system that allows players to be falsely banned if spammed with enough reports regardless of that player’s actual behavior. Twice there have been large threads of players attempting to spread awareness of their falsely banned accounts and twice forum moderators have silenced them. You can read more about that in the recent comments of the megathread linked below. I sincerely hope that your friend is able to get in touch with a human to review your case, but if not, I would highly encourage you to start a megathread compiling posts of others who have had their accounts falsely banned as well. We will not allow them to continue silencing us.
You are not alone in experiencing this bug. Here’s a link to my post in case you’d like to read more about this issue: Comprehensive Thread Of All Top 500/Competitive Bugs. I put your thread under: False Suspension And Ban. Please help in spreading the word about this megathread and other related threads regarding these issues.