When a mechanic shop is insured then yes he/she can be held liable for it.
I rarely post in threads like this but I have to point out that your quote above is a totally incorrect statement. Liability is not dependent on insurance. The aggrieved pilot's ability to collect any judgment may well be dependent on insurance, although I am sure that somewhere there is a mechanic or maintenance shop who/that has sufficient unprotected assets to NOT be judgment proof. Go find him or that shop and sue away.
There are a lot of uncollectible judgments out there just waiting in case the losing party somehow comes into money....
-Skip