Let me just rephrase what you said. Instead of "the science isn't fully decided", which paints an incorrect picture, let's rather say "of everything they've tested in a typical legal vape, everything is essentially harmless. Some of the components haven't been tested."
Saying "the science isn't fully decided" implies "eh, maybe it's dangerous, maybe it's not, 50/50". That's not at all the case. It's almost certainly all harmless. Just very addictive.