Besides that, that shouldn't be the base upon valuing trust ratings.
(Your rating is written in bad english, it's invalid and what you say is wrong./That user has perfect, good english, he surely can't be lying about what he says.)
As a result, without OP getting a 'counter' or unrelated positive feedback from another person on DT or without KWH being kicked from DT (which I think is unlikely to happen),
OP will stay at -2: -1 / +0 (for default settings).
tl;dr: trust scores don't magically 'negligible' themselves.
Ofc, that's a problem when your signature campaign kicks all users with negative trust ratings (or at least doesn't pay them).