I think the trust-issue should be solved by multisig fiduciary accounts like BlackHalo or BitHalo did it... it is much better than calculating a trust score. Here someone who would not do the transaction correctly would loose his blocked assets (Steem or SBD).
New users could not onboard to Steem or use Steem to convert to other currencies as they have no history at the beginning.
With BlackHalo that is not necessary and I think Steem could implement it as well, perhaps your app could add BlackHalo functionality? That would be huge!! (But using an additional artificial trust score is not the right way I think)...
https://steemit.com/steem/@mexbit/p2p-steem-usd-exchange-trust-issue-solved-by-steemhalo
Maybe we can build something like that in!
That would be amazing and a game changer! Excellent!