

(Ignoring sloppy writing as the reason…)
Star Fleet seems to like to compartmentalize information. Examples:
At least post ‘First Contact’ they had hints of the Borg before ‘Q Who’ but kept it quiet. Similarly the Genesis device information was on a need to know basis (although probably for good reason). There was also that Voyager episode based around the Omega directive that only Janeway knew about.
It’s also been suggested in the beta canon that the Gorn are made up of multiple reptile variants. The ones in SNW seem to be raptor based. It’s possible the less agile more tank like variants might show up later.