What makes you think that's what he experienced, as opposed to the well documented temporary side effect of heart inflammation? In my experience I was fine after the first dose and experienced it after the second dose. That is line with what is most common. If it was anxiety wouldn't more people be reporting the side effect after the first dose?
I get that reporting on these side effects causes vaccine hesitancy that isn't good but I don't think people who experience these side effects should be discredited or silenced as a result.
For a number of reasons. First off, over the last 18 months this guy has been in these threads expressing doubt about the vaccine, saying he doesn't trust it, saying he has prior health conditions that make him nervous about getting it, and even bringing up the heart inflammation stuff in the past. He has consistently said he was not going to get the vaccine, that he was going to pass, that he was going to wait until he was more confident that it was safe. Now suddenly, he gets the vaccine and experiences the very thing he was worried about previously, this extremely rare side effect.
On top of that, heart inflammation is not really something you brush off, let alone go for a run with, like he said he did. If he really had heart inflammation he would know immediately once he started running, he'd be gassed and out of breath and have chest pains. And it doesn't go away in just a few days without treatment.
Nobody is saying he didn't experience something real. Anxiety is real, it causes literally all those same side effects and it's a real, physiological response. It is not in your head or made up.