I think it’s great you are thinking of friction free ways of people joining SAFE. i think that is the single most important thing after SAFE’s core.
Just look at how hard it is to join diaspora, and see how different it could have been if they had been able to address that!
I don’t fully understand your scheme, but it made me interested, and I wonder if it the WebRTC / in browser vault approach might work (recently discussed) - @Erick posted about a WebRTC / Javascript SAFE client/vault
It creates a very easy way for anyone to join the network, just by visiting a URL/web page, and to be earning Safecoin anytime they are running their web browser. Since Safecoin is ideal for micropayments on the network, this could simplify your idea - by making even those casual message board users into real SAFE account holders.