The sexual connotation gets its name from the slur[1], because the suit handicaps the wearer. The name of the image editor originates from Pulp Fiction, which uses the sexual connotation.
And most of the commonly understood meanings of the word are rather negative. Nobody hears the word "gimp" out of context and thinks of decorative sewing thread, for example.
[1] https://english.stackexchange.com/questions/40730/was-the-wo...