If you think secure boot is a problem then you probably leave your front door open at night and wouldn't mind if unwanted guests wandered in and messed with your stuff.

So as an analogy, secureboot hands your keys over to a bunch of strangers and you then have to trust them with your house.... stupid idea - I trust me, not some bunch of corporations whose main aim is to make money, my security is way down their list of priorities.

And what makes you think trojans won't run quite happily within the secureboot environment - they're trojans, they'll simply masquerade as something else. Secureboot != anti-virus.