If you are talking about myofascial trigger points that can undergo LTR, it is absolutely well established. Those trigger points are localized contractions of sarcomeres in skeletal muscle. There is a very clear electron microscope image of trigger points that usually shows up in the literature, and although I couldn't find the specific image I'm thinking of online, here is a variation -
The localized twitch response is a further contraction of the skeletal muscle fibers when the trigger point is stimulated, after which the knots are relaxed because the micro-contractions have released. The most current and accepted theory about the formation of trigger points that I am aware of has to do with damage to the sarcomeres and Ca++ pump and the ensuing shortage of ATP. You can google "energy crisis theory" for more details.
Given. The tension they create implicates reflex circuits. That may well contribute to the constant afferent stimulation that affects some but not all the fibers -- possibly through the spindles. Activating the reflex may simply disrupt the abberant signal -- or possibly relieve an exhausted synaptic electrolyte threshold caught in a feedback loop. Activating the LTR reflex seems to be important to the effectiveness
of needle treatment -- which to me begs the question whether it is the reflex arc stimulation that is the proper target rather than the affected fibers themselves.. And the fact that the treatment involves provoking counter-reflex activity -- implicates a key part of the afferent effect of the golgi tendon reflex -- it inhibits the alpha motor neurons in the target muscle with the trigger points -- removing at least one source of a constant action potential that may keep the trigger points actively contracted.
Following your logic -
Practice aikido >
Develop feelings of "loving protection" >
production of oxytocin >
stimulates smooth muscle-like aspect of fascia >
fascia tightens >
develop Ueshiba's level of martial efficacy (and develop trigger points, I guess?)
I have not expressed any such progression -- much less that one-- nor yet concluded whether the involvement of oxytocin on fascia in this context is an operative element, a resultant or signpost effect, or simply a coincidence of association with Ueshiba's religious thought. The Doka don't read that way. It is something not trivially dismissed. However -- the more an more of these connections that I find, I conclude it is less and less likely to be merely the latter.