: I don't see how a soldier in a universe where the primary form of stasis is
: by refrigerating the subject can believe that stasis refrigerant is
: used in bombs, especially since most military personnel in the Halo
: universe seem to be quite familiar with cryo (and how bombs work, for that
: matter - please point me at a conventional or nuclear weapon that would
: for any reason have a cryogenic stasis component).

: I also question the part where it's not the kind of bomb they thought it was;
: if it's an entirely new weapon, why did it need the stasis refrigerant in
: the first place?

Because it's appears to be necessary for the null state stasis container that was used. There was concern that the container need to preserve the contents and shield them from external scans. So it appears the stasis refrigerant was used to help achieve that. The null state stasis containers are apparently rare and numbered, most belonging to the UNSC. The one obtained by Christian Ramsay appears to have been assumed to be keeping fissile material in stasis since they wanted to ensure no Hawking or Gamma radiation leaks.

The idea being that ONI suspected a small fission bomb was being transported to Sedra, kept in a shielded, hermetically sealed stasis container to mask it from being detected until it was deployed.

It turns out of that what it was really holding was a new radiation projection device using the unique properties of the Alpha Shard element. This infers either thag it was meant to be kept secret until deployed or that the element needed to be kept protected for some reason.