M5 Guru (>2000 posts)
Join Date: Nov 2010
Location: Sanborn, NY
Thanked 252 Times in 214 Posts
I agree with above. It sounds like your mechanic has not done this work before. That doesn't mean he's not qualified. He may just be being cautious and "by the book".
I would also recommend only removing the front clip and doing the work from there. You don't gain much from removing the engine except for the ability to raise the engine higher so you're not bending over... but your mechanic has a lift so that is easily overcome with the engine still in the car.
I would approach him with facts from here, but try not to put him off.
UUC dssr and shifter
Supersprint headers with Tubi catback
JED lightened flywheel
258,000 miles and counting...