I don't think that's it, I haven't used getOneFree so the only entries there would be what vanilla uses, which are all more than one entry.
EDIT: Ah, but the navigator and engineer have getOneFree lists, unlike the soldier which just unlocks. Hmm...
EDIT2: Confirmed, setting getOneFree: [] on the engineer made it unresearchable from start, while navigator (which did not get getOneFree: []) is still bugged. To the bugmobile!