Of the 16 total trains between mumbai and gkp (including weeklies and specials), four (namely kashi, ratnagiri, godan and gkp weekly) run over the route mentioned by you. Of these two were extended from bsb to gkp (ratnagiri being extended post covid).
Anyways, the blogger did talk about reroute of pune lko and not some mumbai gkp train which was a proposal in irttc 2021.