It seems to me they should let you accept the risks of using unsupported software, not denying you that right.
Not that I don't agree with that, and I'd even say they should just have a "it activates" without all the hoops policy, if that's what the maker wants to do.
But it costs a boatload of money to keep the infrastructure in place to activate and track activation of software. And I can understand why makers do not wish to do this.
To me, it's no different than automobiles. There is a legal period where the makers are required to provide replacement parts and other support for the product, but after that, you're on your own entirely. If you so happen to have purchased a product like a Ford Mustang or Chevrolet Corvette or any other car that had a huge market, there will be an aftermarket that's supporting you because they can make money doing so. But if you bought something like, say, a Checker Marathon or you own a Studebaker or Delorean or similar, you are on your own as far as sourcing NOS if such exists or having custom made when it doesn't. It's not up to the makers to support you in perpetuity.
But allowing software to activate "in perpetuity" likely also carries certain legal risks and obligations with it. It should be considered much more like milk, that sours after a certain point. I personally don't think our industry at large has done ourselves, or our clients, any favors by, over the years, trying to extend the life of out-of-support software indefinitely. I hope that practice is changing.