I completely agree; nothing here is conclusive at all. I just can't stand flippant statements like, "the data is clear," when it isn't, at all. Those kinds of people are directly contributing to the social divide about science.
There are now a multitude of studies indicating the prevelance of myocarditis from COVID 19. Many of which are broken down by age, so you can see how much higher the prevelance is vs vaccine side effects.
We have a pretty good idea of how bad the myocarditis issue for COVID is because we had a good long time without a vaccine. There were very large increases in myocarditis in 2020 vs 2019.
The real problem is that people like yourself jump to the first contradictory study you can find and tout it as proof or simply muddy the water from what many of the experts are saying. The reality on this particular issue is that quite a bit of research has already been done. A quick search will pull up multiple studies on myocarditis rates with covid, most of which have age breakdowns.
OP's preprint show a rate per million of 537 for young adult males on their second dose.
I would say the research definitely isn't conclusive yet. For young adults, whether the vaccine is safer than getting COVID is an open question, but we do know the absolute risk for both (vaccination or getting COVID) is small.