As Tony states, this is an awkard one because of how devices are registered within Windows. Windows Class GUID is not your only option though, and devices can be matched by Device ID as well...
https://docs.microsoft.com/en-us/windows-hardware/drivers/install/identifiers-for-scsi-devices
The above MS article gives a few examples of the types of SCSI devices that can be identified by Windows' SCSI Port drivers, as well as an example of one for a disk drive. If you specifically want to block only SCSI Disk Drives, then you may want to try the below Device ID:
SCSI\Disk*
This is not exhaustive however, so you will need to perform thorough testing.