Running the A/C when in "Defrost" has been a thing since before Fido's great-granddoggy was a pup. I learned about it in trade-school in 1980, and it was old-news then. I bet it dates back to the '50s when A/C was integrated into the heater/defrost system, instead of being an add-on in the trunk or hanging under the dash.
Defeating the A/C operation when in "Defrost" mode is nuts and counter-productive.
The A/C dehumidifies the air, which makes the defroster more efficient/faster/better. The "dry" air is then re-heated. Hot, dry air is better at removing windshield fog than hot, moist air.
The A/C compressor is protected against cold-weather damage by the low-pressure cutout switch, which also protects the compressor if the refrigerant charge has leaked-out. It's a well-thought-out system.
Screwing this up makes no sense at all.