I think your conclusions -- "the strict press was superior to the push press for shoulder activation" / "a muscle generates the greatest force from a position of being stretched" -- are correct. I don't really pay any attention to/assign any value to EMG studies, since many of them have shown that the hamstrings are not involved in the squat. This assertion -- "the deltoid activation is isotonic in the first half of the lift and isometric in the second half, with the triceps providing most of the force in the second half of the lift." -- is probably correct. This -- "the push press, by using momentum to get out of the bottom of the lift easier, is essentially skipping over the part of the lift that has the greatest deltoid activation" -- is certainly true. Partial reps do not yield maximum gains because the whole ROM is not trained, and deltoids are obviously not the only muscle group in the movement. This -- "if such was the case we would all be doing partial reps for maximum gains" -- sounds like bodybuilder talk, gains being equal to mass improvement for his favorite muscle group.
But really, I don't think I understand your question.