Learn English – “Someone else took them helm”

In the excerpt, editorial is essentially being used as a synonym of commentary. It's odd that neither of the (generally good) dictionaries you looked in mention this metaphorical meaning. Dictionary.com lists it as the third definition (emphasis mine):

1. an article in a newspaper or other periodical presenting the opinion of the publisher, editor, or editors.
2. a statement broadcast on radio or television that presents the opinion of the owner, manager, or the like, of the station or channel.
3. something regarded as resembling such an article or statement, as a lengthy, dogmatic utterance.

This usage of editorial usually has mildly uncomplimentary connotations, either because the statement of opinion was too lengthy, or because (as in the novel) it was being expressed in an unwelcome setting.

OP has misparsed the usages. You can have something on someone (you know something "secret" about them, giving you power to "blackmail" them). But you can't have something to [a person].

The cited usages are versions of the idiomatic there's something to it, meaning it's not a completely daft idea - there's at least a grain of truth in it. Or perhaps there is some point in doing it.

EDIT: In the same general area, it's worth noting there's nothing to it, which usually means it's easy. It is sometimes used to mean the exact opposite of the usage under consideration here, but I think most people use there's nothing in it when they mean it contains nothing of value or truth, though it can also mean there's no difference [between two things being compared].