RE: I guess I didn't realize there was a specific carve out that allows tax preparers to do FBAR.   Any idea where that is?

 Bob, please don't tell me I'm UPLing by listing the following.

1.  For practicing tax law: 5 USC §500(c) (2015), in conjunction with Section 10.2(a)(4), Circular 230, definition of "Practice before the IRS".

2.  For e-filing FBAR, per some guy from Lacerte Support. 

Oh just kidding.  I would actually cite the carve-out from the horse's mouth:

https://www.fincen.gov/individuals-vs-cpa-attorney-and-paid-tax-preparers#:~:text=Who%20is%20conside....

Specifically, 

Can an attorney, CPA, or an enrolled agent submit an FBAR via the BSA E-Filing System on behalf of a client?
Yes. An attorney, CPA, or an enrolled agent always may assist its clients in the preparation of electronic BSA forms for BSA E-Filing, including the FBAR.....

I never looked beyond the above, though I imagine there has to be some code or regulation that says "the Top Cheese of finCEN shall have the authority to promulgate ....."