Strength must be -1 for someone to drop off DT1, and the effect is immediate, not next week.
Obvious if anyone starts including random users in their DT network then they should be "~". I have ~ed Vispillio
I wouldn't worry so much about him and his feedback (your profile looks fine to me), because anyone can see his red colored profile and he didn't provide any proof for his claims.
I was not worried but surprised to see a -1 rating on my profile while checking with ;dt suffix on the profile URL :-D