Interesting looking crack - seems to be quite uniform around the shell.

I'd say the frame is junk. You would have to un-glue the carbon back end before any type of weld repair is performed. 7005 does not need heat treat but not sure if more heat cycles are good for the metal.

Regarding not facing the frame, this is a VERY poor excuse. I'd call the manufacture on this and ask to see documentation on where they instructed the dealer to do frame prep. If the frame came with instructions to face the shell then they may have a point. Otherwise, they are blowing smoke.