I believe this is something called credit card churning. There's even a reddit forum for it.
https://www.reddit.com/r/churning/
Technically not illegal.
When a mechanic shop is insured then yes he/she can be held liable for it. That's what being insured means. Furthermore, that reply was not addressed to you nor do I care about how you buy your planes. You're obviously not a very good mechanic if you're going to get this triggered by a simple...