But probably far less who will actually update their lists. Having said that, 10 people with 10 merits (and 1 with 100) trusting you is not a particularly high bar to be set. I would worry about potential scammers either buying or trading merits their way on to DT.
If I'm not mistaken, 200 sMerit is enough to create 10 DT1 members: Send 20 Merit to 10 accounts, send 10 times 10 Merit to the last account, and give all of them this Custom trust list:
myfirstDT1
mysecondDT1
mythirdDT1
myfourthDT1
myfifthDT1
mysixthDT1
myseventhDT1
myeightDT1
myninethDT1
mytenthDT1
myeleventhDT1
That puts all accounts with 20 Merit on DT1, only the account with 100 Merit isn't trusted by someone with 100 Merit.
A bored Newbie with a hacked Legendary account could pull this off. Then exclude all other DT1 accounts, and the hostile takeover of the trust network is complete (until manual intervention).
Suggestion: Shouldn't there at least also be an Activity requirement?
There should definitely be an activity requirement in addition to the merit requirement being increased. Now it is even more dangerous to add inactive accounts to any kind of list!