Tivoization

[andry-dev]

Hi, in a group of friends we were discussing the merits of Parity with respect to other copyleft licenses like GPL v3 and AGPL v3.
One of the members posited the matter of Tivoization, which doesn't appear to be covered in the text of the license.

Suppose that I release a software under Parity and another entity forks it and redistributes it for its devices. So far, the other entity is required to not relicense the fork. Now suppose that they force their devices to accept only the versions of the software that are digitally signed with their secret key. The user of my software cannot load the original version or other forks on those devices, because it's not signed with their key. This scheme is known as Tivoization.
(A)GPLv3 has a mechanism to still force the other entity to allow the user to change the software, preventing Tivoization.

Suppose another scenario (possibly unique to Parity?), in which I'm releasing software doing Tivoization, that is the software is released as Parity and I create some devices which enforce a signed version of my software. Forks can exist, but they are practically impossible to use, in fact I can still use contributions from other folks. Thinking about this case, since I'm the copyright holder, it appears that no license can prevent this (?), since I can always dual-license.

I wanted to ask if both of these scenarios are against the spirit of the license, that is, if text against Tivoization is missing on purpose or not.
If so, what clause can be added to prevent Tivoization (at least the first scenario)?

Thank you for your time.