If you're going through the trouble of epoxying USB ports, you could probably epoxy the mouse to its port as well.

Or just monitor connected USB devices and shutdown if something unapproved is installed, a la USBKill.

https://en.wikipedia.org/wiki/USBKill

If mouse is epoxied - cut the cable, cut and splice in a male->female cable, connect your device.

Doing so would trigger a USB disconnection event, which under a sufficiently paranoid ecosystem would immediately terminate the entire enclosure and lock the door and call security.

I think they are trying to discourage accidental use of/the urge to use the USB ports.

Epoxy is a pain, just use a sticky connector envelope instead.

USB disconnect disabling whole USB host is trivial to code. You would disable on disconnect instead of whitelisting as there can be USB host bugs. Add a boot password so that only admin can start the machine...

Plus the are solutions where drivers are also put in a VM to further reduce attack surface.