This is all probably correct and it probably is the path of least resistance to bring him along for at least the first couple of months of next year.
In general when this conversation comes up though, it seems like some downplay the impact of him holding down a roster spot; that's one less 26 man spot for someone who could be acquired through free agency, trade, or from the minor leagues, and subsequently one less 40 man spot for someone who could be added as well. Granted, as Ed has suggested in the past, concerns about the 40 man can be overblown as there is chaff that can be removed, but if you are an incoming GM who wants to improve the roster via trade or free agency and / or evaluate the talent that this org currently possess (which he no doubted has been charged with doing), that roster spot being off the table is not at all ideal.
And it's easy for us as fans to look at 2023 as a write off, but Harris did not give that impression at his presser nor in his work with the Giants; he sounds like a man who wants to improve the roster as it is currently built and put the best possible product out on the field. I love Miggy, but he's an impediment to that for better or worse.