I don't see why it couldn't still have a performance tune done on it.

That is of course as long as it doesn't eliminate the computer update/flash.

The U61 reprogram is about the cruise control.
https://static.nhtsa.gov/odi/rcl/2018/RCRIT-18V332-2370.pdf

The fault handling strategy of the Powertrain Control Module (PCM) software on
about 1,574,200 of the above vehicles does not remove positive torque requests
from the engine controller if the CAN-C bus stops communicating while the cruise
control is requesting positive torque. In the instance of a short in the vehicle
causing the CAN-C bus to stop communicating while the cruise control is active
and the vehicle speed is below the set speed such that the cruise control system is
requesting positive torque at the exact moment of the short, it is possible for a
positive torque request to be locked on the PCM which may result in either the
vehicle maintaining its current speed or possibly accelerating. If the driver does
not shift to neutral or apply the brakes to stop the vehicle this condition can cause a
vehicle crash without warning.