You have 12 year old brake fluid and this guy does not think that is an issue?
I'd not listen to anything he says after hearing that.

My 07 has 38,000 on it. It just got differential and brake fluid (as well as new street performance pads, those OEM pads are HORRIBLE); I've got to get shorter bits to do the transmission (Manual) and will get to that in a few weeks.

Here is something you will think is surprising - I sure did. My differential fluid was down about 1/3, it is leaking out the right seal, but ONLY when MOVING. No oil on the floor. Had I not done the service, I'd not know that I was leaking. Your car is super low miles, it sits way too much - the chance of leaks or other issues is higher with your car than mine. I'd get under there and see what's going on. Make sure SOMEONE is paying attention to the amount of fluid that comes out.

But it's your car, and if you trust him (you don't or you would not be asking us), then .............................................