Thank you to the authors for taking the time to write your thoughts in this paper. You have an interesting and novel hypothesis. As a non-expert, it seems as plausible as any other model of ME/CFS I've seen thus far.
I don't think the wording on topics that could be confused with BPS is terrible. The entire paper makes it very clear the authors don't have a BPS view whatsoever. The only thing I wish was clarified would be this
In this context, we cannot rule out the possibility that the higher rate of diagnosis of ME/CFS in women is in part due to a greater ‘health vigilance’ in women – of central nervous origin.
It could be worded to explain patient's behaviors directly instead of making it sound "psychosomatic", for example "We cannot rule out the possibility that the higher rate of diagnosis of ME/CFS in women is in part due to a greater likelihood for women to seek medical care and diagnosis".
You explain concepts like scientists should, but don't unfortunately. Nowadays everything is wrapped in jargon and buzzwords. It seems more about trying to impress the audience than laying out a logical argument. There's a lot of common sense in this paper. Using the epidemiology to suss out possible causes is pretty clever because epidemiology is one of the few things we know reasonably well, compared to all the biochemical studies, that mostly find subtle abnormalities that don't explain much in terms of causation. I'm also glad you're upfront about the lack of certainty behind your ideas, unlike a lot of scientists who try to argue they found it when they haven't, or only found preliminary evidence. It's all solid reasoning.
I can't really speak too much about the specifics of the model, but you manage to explain most of the observed features of ME/CFS, like the predominance in women, ages of onset. And there's a lack of obvious test results because it's a potentially local signalling problem. I don't know if it's specifically a problem with FC gamma receptors, but the idea it's caused by a signaling problem in the immune system, inducing something akin to chronic sickness behavior (but without activating all the pathways you get with a cold or flu), makes a lot of sense.