CCS/CC2642R: Where did the _bim_var variable go in the latest version of cc26x2r1lp_bim_onchip

Tool/software: Code Composer Studio

I have used OAD on the CC2640R2F and the bim app code uses a variable _bim_var to determine if the bim needs to boot into the persistent app  or the real app. But with the CC2642R version of the bim it looks like the app code writes to flash to tell the bim to boot into the persistent app. Why did that change why would writing to flash be better than using the low leakage RAM?

Thanks for the help.