Yup. I assume there is plenty of value to be found selling donor boards and other parts of the iPhone. Not saying it's a repair shop's fault if they end up with motherboards of a stolen phone, but if I were a thief dealing with an activation-locked phone, my first idea would be a jailbreak, and if that fails, then disassemble the phone and sell the parts.

Presumably thieves already do these things (and more sophisticated things) to extract value out of stolen iPhones.