It's not so much the mount that's the issue, it's the 52mm of cast and machined aluminum that holds the mount and the sensor aligned. What's being suggested is that Red not screw the mount onto the body and instead onto a standoff that keeps it aligned with the plane of the senor made of invar or some other thermally stable material of their choosing.
That being said a steel mount front PL is a still good idea. I think invar may be a bit brittle for the actual mount, but I'm not sure of this.
Thanks for your care and attention!.