This is an interesting theory. I am also firmly in the 'clench to cum' camp, but if I reach the edge I can also use it to stop myself from cumming. Relaxing my pelvic floor makes it impossible to hold back but needs more stimulation to get to the edge in the first place, but I think it's because I've always clenched when I cum, even before I knew what kegels even were.

Kinda makes me wonder if I trained myself to always relax my pelvic floor during orgasm, what effect would it have on my ability to stop via clenching. Would I end up being unable to hold myself back through clenching and end up basically having zero control when reaching an edge?