AnimationOverrideController Inspector does not allow an AnimationOverrideController to be used as the base controller

Steps to reproduce:
1. Open the attached user's project "1764160-anim override controller.zip"
2. In the Project Window select Animation Override Controller "c"
3. Drag and drop Animation Override Controller "b" from the Project Window on "c" as a base controller

Expected Result: drag and drop is successful
Actual Result: AnimationOverrideController Inspector does not allow an AnimationOverrideController to be used as the base controller

Reproducible with: 2021.3.35f1, 2022.3.20f1, 2023.2.11f1, 2023.3.0b8

Testing Environment: Windows 11
Not reproducible on: No other environment tested