OP, your original question is if it would reflect "good" or "bad" on Mom for complaining about the distance to school as it currently is and then increasing the distance with the move she just announced, almost doubling the distance from 25 min to 45 min (not taking snowy/icy days into account). Mom may have complained about the distance before, but unless that complaint was put forth in family court and we have the context for the complaint, I don't know that the court will care.
Nextwife may have hit the nail on the head, but only time would tell this, there is no way to know this at this point or not unless there are other factors that would line up to support this theory:
As for the current mediation, if I were Dad, I would certainly fight for the distance to be minimized, not increased.