Recieved some additional info:
To meet requirements from the federal government, the McAfee Firewall Enterprise (Sidewinder) is unable to write to the eUSB device at any time. If it is attempted to write to this drive under normal operation a Type Enforcement™ (TE) violation will occur.
A tool has been released to update the eUSB image, but that requires a boot to a specific tool such that the eUSB image can be updated to the latest imaging point(s) shipping from the company so that customers with more than one image on the eUSB can standardize on the current solutions that new hardware would ship with. That tool requires the firewall be powered down, and booted to the tool with no networking capabilities.