I don't particularly disagree with what you are saying, but I do feel you are both being overly reductive. Ronaldo hasn't arrived and broken the side with his lack of pressing. He hasn't joined a well oiled functional system and stood out like a sore thumb. Low workrate when the opposition are in possession is characteristic of all our forwards, bar Edinson Cavani and Jesse Lingard. One of these lads struggles to start even half of our matches, the other was sent out on loan last season. All of the others - Rashford, Martial, Greenwood and Sancho- are poor on these metrics relative to other players at other sides. You can substitute any of those guys in for Ronaldo and we'd have the same outcome.
I think people are overlooking that our results were spotty and indifferent in the final part of last season too. One thing I highlighted previously is that we haven't won any of the last 5 matches that Cavani has started stretching all the way back to April for instance. It is been apparent for a long time that sides progress down the field against United far too easily, and it is so much more obvious watching games in person again with a vertical perspective from the Streford End. Just replacing Ronaldo in the XI is not going to fix these issues.
Rather than just bemoaning Ronaldo's lack of pressing, a solution needs to be found to make Manchester United a better side, whether the man implementing it is Ole or someone else.
I posted my collected thoughts here yesterday. Personally, I would want to maximise the goals that Ronaldo can offer and adjust the role of Bruno and my wingers, making different demands from them. If Sancho and Greenwood can't do what I need from them, then Lingard will be a regular starter. You want pressing from your forwards and attacking mids? Now here's a player who presses highly compared to his peers. If I going to accommodate one player with lower workrate out of possession, then it will be my centre forward and not my left or right winger.
Now, you can argue that Ronaldo doesn't offer enough out of possession to justify his goals, but what's your solution with this squad of players? It's a big call to not select him, but still indulge Sancho, Greenwood and Rashford's lack of workrate without the ball. Last season doesn't offer much to suggest that we were actually better off without Ronaldo.