Anyone who wants to should be able to buy such a device, as it isn't like any of the machine code you are getting elevated access to is even secret (you can download, from Apple, unencrypted copies of the entire operating system). (You can try to make an argument that this is about keeping you from getting access to third-party encrypted assets to prevent some aspect of piracy in the App Store, but this doesn't accomplish that either as you need only have a single supported jailbroken device for that to be easy, and the world already has millions of those and you can't really prevent them as the act of fixing bugs discloses the bug for the older firmware.)
The real problem here is that Apple is so ridiculously controlling with respect to who is allowed to develop software (in Apple's perfect world, all software development would require an Apple license and all software would require Apple review)--in a legal area that isn't really conducive to that (see Sega v. Accolade, which was important enough to later ensure permanent exemptions on reverse engineering and even jailbreaking for software interoperability purposes in the original DMCA anti-tampering laws)--that they are even working right now on suing Corellium, a company which makes an iPhone emulator (which again, has strong legal precedent), in order to prevent anyone but a handful of highly controlled people from being able to debug their platform.
Apple just has such a history of being anti-security researcher--banning people like Charlie Miller from the App Store for showing faults in their review process, pulling the vulnerability detection app from Stefan Esser, slandering Google Project Zero, denying the iPhone 11 location tracking until proven wrong, requiring people in their bug bounty program to be willing to irresponsibly hold bugs indefinitely so Apple can fix things only at their leisure, and using the DMCA to try to squelch research via takedowns--that this ends up feeling like yet another flat gesture: they should have done much more than this device at least a decade ago. I'd say Apple is in store for a pretty big fall if anyone ever manages to get a bankroll large enough to actually fight them in court for any protracted length of time :/.
The real problem here is that Apple is so ridiculously controlling with respect to who is allowed to develop software (in Apple's perfect world, all software development would require an Apple license and all software would require Apple review)--in a legal area that isn't really conducive to that (see Sega v. Accolade, which was important enough to later ensure permanent exemptions on reverse engineering and even jailbreaking for software interoperability purposes in the original DMCA anti-tampering laws)--that they are even working right now on suing Corellium, a company which makes an iPhone emulator (which again, has strong legal precedent), in order to prevent anyone but a handful of highly controlled people from being able to debug their platform.
Apple just has such a history of being anti-security researcher--banning people like Charlie Miller from the App Store for showing faults in their review process, pulling the vulnerability detection app from Stefan Esser, slandering Google Project Zero, denying the iPhone 11 location tracking until proven wrong, requiring people in their bug bounty program to be willing to irresponsibly hold bugs indefinitely so Apple can fix things only at their leisure, and using the DMCA to try to squelch research via takedowns--that this ends up feeling like yet another flat gesture: they should have done much more than this device at least a decade ago. I'd say Apple is in store for a pretty big fall if anyone ever manages to get a bankroll large enough to actually fight them in court for any protracted length of time :/.