Superfish was preinstalled software that could be removed by following a few steps (or installing a clean OS.)

Boot Guard is a hardware-level protection that cannot be removed or disabled.

Of course the latter is (theoretically) non-malicious, but something of that permanence disturbs me far more than some easily-removed malware. The fact that it is used to ensure that the OS and everything above it is in an "assured state" means that it could also be used to prevent users from uninstalling "approved" software like Superfish.