You keep saying "non Tesla shop" when what it appears you mean is "Non Tesla CERTIFIED" shop. BIIIGGG Difference. Tesla can not tell you that you have to take it to a "Tesla shop". They can specify that you need to take it to a tesla certified shop" (which absolutely does not have to be Tesla owned), to maintain warranty coverage.
On a side note, I am still trying to figure out why over the past few months people have the impression that this site has anything at all to do with insurance valuation. The number of first posts where people are asking, in various ways "is this totaled?" is very strange to me.