Hm, "fast boot" being done deliberately to foil entering the firmware? That sounds a bit too tinfoil-hatty.
I think this particular USB issue is probably more in the nature of an "unexpected benefit" rather than a deliberate design. At least at this point. But I still wouldn't put it past Microsoft. I've dealt with them since the days of DOS. And one thing I have learned is not to underestimate their aggressiveness or willingness to push the envelope of acceptable behaviour when it comes to selling software.
Of course, now that this has been pointed out, it will be interesting to see how fast (or if) they fix it. Passive-aggressive responses have served Microsoft almost as well as their all too frequent stonewalling has. My guess is they won't fix or change their fastboot 'requirement' to accommodate any objections.
And why should they? This is a company that routinely thumbs its nose at national governments, regulatory agencies - and frequently ignores court judgements that go against it. Bill Gates used to openly state his goal for Microsoft was to be an absolute monopoly in which every computer on the planet was running Microsoft software. Eventually he learned that smart CEOs don't use the "M" word in public. But the fact he no longer said 'monopoly' didn't change the company's attitude or goal.
Tinfoil hat? No...I don't think so. Not if you've paid attention for around the last ten years to what’s been going down in the tech world. And especially not
when it comes to Microsoft.