The classic term vaccine is being misapplied to the new mRNA treatments. Not sure why someone would

have issues admitting that unless they somehow felt that this fundamentally threatened their beliefs.

The 2 shot COVID "vaccines" still has significantly worthwhile preventaitive value, but you bring up a good (if esoteric ) point. It further demonstrates that this topic is religious dogma to some people.
They exhibit behavior seen with zealots who want to force their beliefs upon others rather than have frank and open discourse.