Exceptions are things that happen once or very infrequently. What happened here wasnt an exception
1. Enslaves Danger in the DR and uses her against her will to train the X-men
2. Uses TP to simulate training to the Lost X-Men, they get killed and he mindwipes Scott's memories of his brother
3. Has sexual relationship with his mental patient, Gabrielle Haller, producing a baby, which was a form of rape
4. Completely mindwipes Magneto, resulting in Onslaught
5. Faked his death multiple times
6. The Xavier Protocols. He methodically thought out how to murder each and every one of the X-men that he enrolled in his school
7. He took in Beast and erased his existence from his entire family
8. Used TP to manipulate Wolverine into joining the X-men as his weapon
There's alot more. One has to be naive to pretend as if Xavier doesnt have a shady past and this all started now with Hickman