Not totally unique. I've read posts by a few other PWME who were continuing to do bodybuilding at levels way beyond my bike rides. I think outliers like myself are useful for ruling out some theories about ME and PEM. It's not absolute ruling out, since there could be possibilities where a theory is correct, but there are unusual circumstances where an individual has an unusual bypass/correction mechanism, but it still helps decide which theories are more likely to be worth investigating.
Yet another variation: even the activities that did trigger PEM never resulted in more than a day or two of feeling lousier. I think food intolerances caused more severe symptoms that PEM did. Microbiome changes (so I assume) caused significant raising of my baseline severity, but could switch off (and on) abruptly. I think that reflects chronic triggering of more severe symptoms, rather than a change in the mechanism that causes the symptoms.