The reasoning I’ve heard is that Bluetooth traffic is easily snoopable without physical access to the device. Someone could potentially steal password keystrokes while sitting outside the office building, on the other side of a window with the shades drawn, whereas with USB you still need to get past the physical security and be at their desk.

In my company USB port is generally disabled for storage and docks, but HID devices, like keyboards, work

Yes, that's weird. USB is a worse attack vector than Bluetooth.

I know, it seemed to me like a pretty arbitrary policy as well, but what can you do other than turning limitations into opportunities? ¯\_(ツ)_/¯