What I hear you say is: This would be convenient and easy for the user. Doing it differently, in a safer way that's not problematically under scope for data protection regulations, would be more effort, not what you're used to and "messy". Certain useful features seem like they'd require more upfront work and the while system would be more complex and unfamiliar.
How is that relevant? None of that changes what you're actually asking about or makes it a good approach. I don't see how it'd make it either safer or less legally problematic?
The trust comes from the association. You can't remove (or keep private) the association and expect to not have to separately rebuild the trust as a consequence. That what you are trying to do is made is inconvenient in GPG is quite intentional I believe. Or maybe I misunderstand your motivations, it's a bit ambiguous and you leave a lot open for interpretation.