My LBS knows me by name, and knows I don't buy everything from them... In fact, I have never bought a bike from them, and have had them do some work for me on a few bikes.

If it is a good shop, they will appreciate your business, and treat you well, if not, then that is an issue with the shop, not with which components are attached to your bike.

I do tend to remove accessories from my bike that aren't relevant to the work I am asking them to do, if they are easily removed, whether I bought them there or not... I assume that it makes the work easier for them to not have to reach around my bags etc.