The problem, IMO, with some of these statistics is you need to look at what percent got jets when those who are Admirals now were winging. IIRC, 25+ yrs ago, Rotary was notably less than the current 50-60% of NA.
Once you correct for old platform distributions, I'd guess any remaining difference is due to primarily two things:
1) Opportunity for major command at sea, which is why some helo bubbas whine about making a helo CAG.
2) Currently, almost all VFA/VAQ skippers go to sea and get ranked by a CAG, while EXP helo skippers stay ashore and get ranked by a CDRE (possibly behind an FRS bonus CO). 25 yrs ago, HS was the only CAG-ranked helo community.
The Jet v. Helo distribution among NAVAIR flags seems much more proportionate, if anyone cares.