I can do all these things myself - compromise any standard off-the-shelf PC given physical access, add persistent viruses to the firmware of consumer hard drive

I can do all these things myself - compromise any standard off-the-shelf PC given physical access, add persistent viruses to the firmware of consumer hard drives given physical access, trick a sysadmin into installing something, become a package maintainer and add some backdoors, etc. So I don't think any of what you've said says anything about the NSA's capabilities, and it certainly does not let us conclude that UEFI is compromised in some way beyond being typically installed on firmware that's not hardened against physical attack (which is also true of Coreboot, traditional BIOSes, and everything else).