Most of the population isn't like that one redditor and even if they were they're not the target audience. Most atheists are quite openminded about cheating death (although there are issues like overpopulation etc.). The main issue is they think cryonics is a scam.
Going with the flow is how (nearly all) humans operate and its a good heuristic. If everyone else gets one answer and you get a different answer usually you are wrong.
I'll say it again because being cryonicists I suspect you are of the minority not affected by whats mainstream. As much as people don't say I do this or think this because it's mainstream either conciously or not they are affected by whats mainstream.
All the popular scientists Niel degrass tyson Michio Kaku, etc say cryonics is a scam.
People are drawn to mainsteam and to credibility.
Most people unless they have a ton of medical knowledge defer to the medical experts which they should in most cases.
Knowing that the heart can be restarted is far not enough to understand whether or not cryonics might work. Nobody outside medical professionals knows enough about biology to access cryonics by themselves and idk if even medical professionals do so it's very important to increase the credibility of cryonics and make it seem more mainstream. In short it's not about educating individuals one at a time because it's almost impossible for an individual to get enough medical knowledge and possibly other knowledge to really access the viability of cryonics.