So comets have different traits, somewhat different chemical makeup, and slight differences in personalities...Why should that come as surprise?
It shouldn't!
Comets have plenty of frozen water; no one disputes that!
Comets have plenty of olivine rich dust; no one disputes that!

The so-called conflictary data on comets is basically minor detail stuff;
a tempest in a teapot, so-to-speak.

What these planetary scientists are endeavoring to do, to keep the paychecks coming in, is to magnify the "minor unknowns", as far as
comets are concerned, to try and interest the taxpayer into paying
for more deep space missions to comets...

Can you blame them?...even if they try to do so by hook-and-by-crook?