Sure, it could be a J&J effect, or it could be spurious, but this is the best evidence we have right now, so if you're a clinician with someone who came down with POTS right after getting vaccinated (this was the premise, remember) then if you're going to follow the principle of evidence-based medicine, you should advise your patient against getting another dose especially if they've already had Covid (this is also the premise, remember) because they're already better protected than the typical twice-vaccinated person. You should not advise typical patients to avoid vaccines because of POTS: firstly, POTS is fairly rare, and secondly, Covid is a considerably larger risk factor, so even if the vaccine is a risk factor, the prediction is that avoiding vaccination would raise the danger for the typical patient.

But my meta-point is that you repeatedly draw hasty conclusions from your prior beliefs (and an uncharitable perspective of those who disagree with you in some area) without doing due diligence on information that is presented to you, and then blame the person you're talking to for misrepresenting things and/or not spoonfeeding you the exact result. This doesn't exactly recommend itself to me as, "Oh, yay! I'd like some more of that, please!"

So, anyway--if we cross paths in the future and there's reason to interact, sure! On purpose, no thank you, not unless you conduct yourself differently!