He's saying don't blame the Buell. It's not the bikes fault the bearings failed. Your wheel is probably fine. Buy bearings, buy a bearing spacer, RTFM, and you could do the job yourself.
It sounds like you have a good relationship with your mechanic and thats great. He made a mistake by not researching an easy fix. Understand no one is perfect, and it's up to you if you want to beat him up about it or let it ride. A relationship with a mechanic is exactly that. Give and take. He should have been better the that, and he will absolutely know he was in the wrong when presented with the Service Manual.
You have an opportunity to politely have him correct the problem and keep a good relationship with a valuable asset. Unless you want to start all over with someone new. I hear 34:19 is single