Is This Ban Deserved? If Not, Could it be Reformed/Revoked? (Account Security)

One of my friends got his account hacked by another friend, and he didn't find out until he got home around 9pm. The friend playing on his account was ranking on it to help another friend out, and he played and won around 3 ranked games until the owner got home. Upset with how the privacy of his account was confiscated, he tried to change his password but he forgot which email he used for his account. He notifies Riot and decides to tell them what happened, and they permaban him because they believed he was getting boosted. He didn't even care for rank that much because he made it to Gold and just played norms/occasional rank for more serious competition. He spent around $500 on a 3 year old account and had no disorderly or toxic conduct prior to the ban, and this would be considered his first "offense". Our friends to this day still make fun of him for telling riot another person was on his account, but should he really be penalized for telling the truth and trying to adhere to the ToS? Only an idiot would admit to having another person on the account because it goes against the ToS, yet he decided to tell the truth, knowing how the situation looked because he had faith in the fairness of tribunal. He saw what was going on and did what he thought was right by notifying Riot to prevent it from happening again, so was this ban really justified? And if so, if a situation where you need help from Riot like another account being confiscated, how much information about the situation should we trust to Riot when something that seemed innocent got someone permed? Yes, account sharing goes against the rules, but is it account sharing if that person was unwelcome and hacking the account? It was a simple case of being able to change the password to something more secure, but I guess it got muddy once he contacted Riot.