I think you may be right that I misunderstood. I think the user had this misconception. I remember reading a report that looked into what people wanted from encrypted comms, and found devs more worried about surveillance capitalism and open-source, while users didn’t much care as long as it didn’t expose them to state or quasi-state oppression. Physical safety reasonably trumps more abstract ideals.
This is a solution to the “I have no secure channel to transmit my keys” problem. If the problem is not there, the solution is useless. 
I think it could be implemented as a webXDC app.