My interpretation of that post is that Montgomery had a similar profile to Merrill through 2023 and Merrill managed to get to the majors the next year so it isn't out of the realm of possibilities that Montgomery could grab the starting SS next year, especially with a potentially more competent MLB coaching staff next year. It's very unlikely but not completely impossible.
Also, I don't really understand all the pessimism surrounding Montgomery, we all knew that he was going to be a raw project with tantalizing physical tools and up until last season he's exceeded all expectations. Even last season he struggled at AAA as 22 year-old still learning the game, but reading the sentiment about him on here and you'd think he was a 28 year-old journeyman.