yes quite possibly but from what I can see rhaphs have no problem gulping big fish. None of the other rhaphs developed the same issue. I had 7, which isn't a great sample set but my impression here is these fish are by design, evolved swallowing machines. Hurting it's own throat like this during a swallow is a serious design flaw either in mechanically or instinctually.
the last survivor of my rhaphs, foot long fish does the same on regular basis with even larger in proportion - fan tails and koi. I used baby fan tails because they are slow and easy to catch. these photos were from about 10months ago.
It's possible the lock jaw/broken jaw whatever it is does not happen during feeding. these fish are especially akward movers. possible it happened crashing into glass or tangle with another rhaph. or as you say it's some kind of thyroid gland, which is part of the immune system, right? Could it be water parameters?