You raise 2 good points. 
I'm not sure about the model and technicalities but I would like to address the other point:
What if Nostr is a bitcoiners only club? What if we are in this closed loop echo chamber, with little tolerance for anybody non-bitcoin? 
The thing Nostr needs the most is to be attacked and to ossify in time. Time will carry enough events (life events) that at any given point a tsunami of people can come suddenly looking for shelter. The protocol allows for them to come in. 
I doubt that day never comes. 
Having said that, I KNOW we are not very well like by the general population, and will increasingly be disliked since the propaganda of the fiat-bodies will rely on this exact premise. 
Just like bitcoin - this all depends on how much freedom is each person's priority.