I misremembered because Niall Quinn said he walked out on them, so I always thought he did a mic drop after destroying Mccarthy and left
I've seen and read dozens of different accounts. There was obviously simmering tension between the two and it just needed a slight tip to set it off. Roy has even admitted since that he was just fed up of playing for him.
He wasn't happy with the setup, he told Mick and he was prepared to leave because he felt they weren't preparing properly for the tournament. He decided to stay. He wanted them to prepare properly, but they got there, the pitches were shit, there was no equipment, no water, no training gear. 3 players already got injured a good chunk of the squad hadn't trained for weeks. He also felt put out because none of the other senior players like Niall Quinn backed him up about it.
He also did an interview with Paul Kimmage or someone like that and said the same things as he had said to Mick. It wasn't well received. Mick basically called him out in front of everyone for faking injury to get out of the second leg of the play off in Iran. So Roy being Roy unleashed his tongue, he'd probably been holding a lot back since Mick had a go at him for being late for a bus years earlier. But he ended up saying a lot of stuff in a short space of time and then ended up leaving.
Both were to blame, maybe Roy could have bit his tongue and stuck it out. But that's not his style, he felt alone and cornered and lashed out. I can see why he's sympathising with Ronaldo, he's sees it as Ronaldo being alone and pushed into a corner and lashing out in his own way. But it's a totally different situation and Ronaldo is totally in the wrong.