[CraigVM]

I utilized the Maestro / SU2 harness with a JVC Maestro compatible HU in my 2013 FRS. While a good bit different than your application in regards to what controls and info yours will provide you with the 2017 BRZ, I believe nothing has changed as far as what effect the Maestro system has regarding audio connec6ions which is none.
The SU2 harness just passes the speaker level outputs of the HU on through to the vehicles connection to the speakers and amp / door speakers. So to my understanding how the OEM aftermarket system works, it will have no ill effect at all as it's 'plug and play" connections will just go between the HU and SU2 harness connection. I would ether want to have the OEM Audio Quick Connect cable in hand to confirm it passes all of the non audio related connections 'illumination, E-brake, vehicle speed, reverse light..." on through or contact OEM audio's tech support to confirm though