Ronaldo is already old and might have a good reason why he doesn't want to partake in the club world football and I don't see anything wrong about his decision. Of course, experience in needed in football much more than strength because lack of experience can make a player miss his opportunity of scoring a technical goal.
Things are really strange to see that CR7 doesn't want to play, he already won the Nation League, he left many people speechless at how a 40 year old man beats a 17 year old boy, you can see his power there, besides it would have been crazy if CR7 had played because he would have sold a lot, and that was what Infantino wanted, but since FIFA has always been so inconsiderate with the best in history, CR7 pays them like that.