The only problem I see with this system is the top xx people will continue to gain more trust and will pull ahead of the rest of the users. You're basically replacing the DefaultTrust with those people.
That's my opinion as well, although I concede it's an improvement over the current DefaultTrust as people will have to manually choose who they trust. I'm not sure how randomizing the list helps though, since the page will be displayed only once.
Instead of showing always the 30 best scorers, an alternative would be to show some random 30 among the 50 top, so people blindly ticking all the boxes don't end up trusting the same set of users.
Randomizing it within a list of people that meet the basic requirements ensures some users aren't displayed more often than others ensuring that statistically people even picking users at random, those on the displayed list will still get trusted more and therefore more trust points.
Over all I think this is moving in the right direction, but the exclusions almost have the same polar opposite effect as the existing default trust list, only via exclusion instead of inclusion. Having higher ranked users override the trust of others that are trusted pretty much keeps the default trust in effect in that sense. Basically, some one could contribute a lot to the community, but if one person with lots of trust excludes them, then all the lower ranked trusts are overridden, basically negating the decentralized component.