Yeah, they are a weak opponent, but it helps with the preparations and getting to know what the best player combo is. Real Madrid hasn't had enough time to prepare themselves before the season starts, unlike the opponents. That there was a very important match.
As for the impending Rodrygo departure this season, I don't think it will happen.
The reason had been stated long term already been communicated by Real Madrid Themselves. But to how tight the Club World Cup was for them they had already plan to actually scrape out any tough pre season as they see the club World Cup ad enough matches that can prepare them just as preseason. This last preseason from the match was simply just to have fun and touch the grass again but they had actually treated the club World Cup as their preseason.
I could remember that this was communicated then that their participation in the club world means they wouldn’t have a tour of all those three or four preseason games. They rather will allow their players to actually rest more for the season than play more preseason games