I think that's an awesome idea. The only thing is I think you should re-evaluate your criteria/point system. The first 3 criteria, email address, BTT id and social media could potentially be used as padding because they're not enough to prove anything by themselves. So that if someone displays a score of 3, you still couldn't really trust him/her because the score could be based entirely on the first 3 criteria.
I think your minimum trust score should mean that you're able to identify the person in case he/she defaults. Moving up the trust ladder would then serve to reflect the dev's competence and ability to see the project through.
I thought the same thing and touched upon those points in the other thread for this. Only the postcard + driver license verification are the ones that really matter. Basically if a coin doesn't get 6/7 or higher, the trust rating probably would be worthless to them. The mobile requirement is also pretty useless and that could be gotten around really easily.
But I can't see any dev signing up for this and paying to get a 3/7 rating or something like that anyway. It's like advertising -- 'We stink, don't trust us' and devs paying for the privilege to advertise that fact.