Solution is simple, Make DT2 criteria same as DT1, if you are not active in last 3 days and have not posted anything in last 30 days then you cannot be eligible for any type of DT list (DT1 to DT4). Only user who are directly trusting by their custom trust list will see their feedback as trusted, for others it become untrusted feedback, no matter user is included by multiple DT1's.
Problem with your suggestion.
DT2(200~) has a wider network of users compared to DT1(56). There is a higher chance DT2 users will eventually go inactive and if you remove them from DT with the criteria as DT1, the trust rating they've given to people might turn to untrusted and will make some users' negative to neutral accounts.