I think I understand the concept. One thing to keep in mind is that my understanding is that RealTracks are musical phrases played over several bars (2, 4, etc), maybe more, maybe less. So if a RealTrack phrase is 8 bars long, and you only want to keep bars 3 & 4, it's probably not going to be possible to 'bar freeze' just those bars.

Yes, saving as a 'block' which is made up of multiple bars could work.

However, I am only speculating on the operation here. I have no absolute knowledge of the internal methods used by the program.

Regardless, the concept is not without merit.
BIAB & RB2021(Audiophile), SonarPlatinum, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M StudioMonitors, Pioneer Active Monitors, AKG K271 Studio H'phones