[_rs]

Oh interesting, that is not at all clear based on the Contacts UI which shows it like any other field

[varenc]

The iOS Contact APIs shouldn't allow modifying this.

You can also try exporting the contact to a vCard .vcf file using the Share Contact button. I believe the iMessage key verification info won't be included. (But as you noted the most important thing is that it can't be modified)

[blurrybird]

That’s just good UI design. Make complex stuff look dead simple.