In my personal opinion, the body shop can not remove the plastic without cutting it or damaging the car ( or both ). This you can do yourself with more care than the body shop. Just have to cut square in the plastic around the spinning bolt. Applying silicone on the top will not help at all, because the problem is under the plastic. This area is like a pocket filling up with water on carwash or heavy rain.

Regards

Larry

p.s. I am with very strong technical inclination, but not auto mechanic. This above is just my advice, but you should look in other posts. They are many experienced and knowledgeable people here that can find better solution.