Perhaps not to back-door them, but to ensure when they (the government agencies) buy from Dell that the supply chain is intact and the BIOS hasn't been tampered

Perhaps not to back-door them, but to ensure when they (the government agencies) buy from Dell that the supply chain is intact and the BIOS hasn't been tampered with during shipping by a foreign agency. Like the NSA did to Cisco routers destined for international customers.