Those 10-20 years old ISRs were mostly an interim 'solution' that were never really liked by the military (not-including Civil Air Patrol) for their intended use & replaced with other systems, especially for field use.
In the New Year's Eve in Vegas context, ICOM should mean Integrated COMsec (radios with built-in crypto as-opposed to an external device), and usually means the SINCGARS family of radios. ICOM is kind of a dumb reference, but it works for them... Note: in the ISR/SIGINT field, ICOM can mean Insurgent COMmunications too.
Plenty of PR photos & some videos on the web show the NV ARNG troops deployed here for NYE, and the 800MHz EDACS Tyco/Harris radios are easily visible on some of the soldiers. Some images show that the deployed HMMWVs do have radios on the mounts. I saw no evidence of anyone carrying the old ISR radios.