This is reverse psychology. To paraphrase:

"The vaxx causes myocarditis, and that's OK. Be pro vaxx. Be strong."

For the vast majority of people, those who are pro vaxx, they believe it is good because it isn't harmful. If it is harmful, if it really causes myocarditis, then it's not so safe. If it's not safe, it's not necessarily good. You might still want to "sacrifice for the greater good," but you probably won't want to sacrifice your children for the greater good.

Things like this cause cognitive dissonance. Cognitive dissonance must be appeased. The only outs are "the vaxx causes myocarditis," or "the vaxx doesn't cause myocarditis, but someone who is "on my side" (pro vaxx) is saying that it does." You have to rectify that. It makes a person think. Thinking for yourself is the enemy of the Cabal agenda. Stuff like this isn't "stupid," it's brilliant.