You must be fucking joking.
"It is high time that the EU or whatnot mandated all computer devices have a free way to disable secure boot should the user want to try another OS,"
The original IBM PC—from whence all modern Windows boxes came—was NEVER intended to be an "open" platform. It was supposed to be a closed platform, just like Apple, Atari's computers, Commodore's, Acorn's, Sinclair's, and every other bloody computer around at the time.
The only reason there's a "PC clone" (for that's all modern PCs are) market at all is because Compaq (and, later, other companies) reverse-engineered their own compatible BIOS ROMs using a clean-room process.and invented the "PC-compatible" market, but—again—HP, Compaq, Dell and their ilk have never, EVER, been remotely interested in letting you install anything other than the de-facto standard software bundle on these machines—i.e. MS-DOS, Windows, and its successors. (Dell were infamous for customising some of their hardware and drivers, so their PCs weren't really as "open" as many people claim.)
These companies have tried to offer alternative software bundles, but every time they've run into the law of diminishing returns: the market for alternative OSes simply isn't big enough to justify the investments and support costs. Most people simply aren't aware that something called "Linux" even exists, let alone what it is. Hell, many people out there will blithely write "Microsoft Office" in the "What is your operating system?" field on a PC support site.
Most people are *ignorant* of IT theory and practice. That doesn't make them "dumb", "stupid" or "brain-dead". It just means they don't share your interests.
To this day, I still have no idea how Cricket works, or who won the FA Cup last time around. I find the whole concept of watching other people exercising and keeping fit utterly absurd and stupefyingly dull. But I don't go around demanding people stop doing it. Whatever floats your boat.
But I _do_ get annoyed when people insist that their "freedom" trumps _mine_, and everyone else's.
"Freedom" is a two-way street.
It includes the _freedom_ to make *any* product *I* damned well choose, and design it how *I* want. I then get to manufacture it and sell it to the public. *I* carry ALL the risk, because, if I've misjudged the market, all the capital investment I'll have made will be lost and I'll be bankrupt. The *market* decides whether I get to be spectacularly rich, make a basic living, or lose my home and the shirt off my back. If you disagree with that, you, sir, are a hypocrite. End of story.
If you want a computer that comes ready-built with Linux (or any other third-party OS), or onto which you can install same, the onus is on YOU to build such a machine, or find someone who is willing to build it for you. If you think your pet OS is so shit-hot, why don't you put YOUR money where your loud mouth is and build your _own_ range of PCs? Offer them to the public, and watch the money pour in! (I can think of a few ways you might be able to pull it off, but none involve following the traditional PC industry sales models. Hint: Red Hat.)
Like it or not, you have no right to demand that _other companies_ sacrifice _their_ design freedoms to meet your petty demands.
Get off your arse and build your own PCs. Nobody's stopping you. Not even Microsoft.