Your estimates don't consider the impact of those 6 million people subbing to Game Pass, or even half of them doing it, and the increase in MTX spending they would engage in.
10m people on PS buying COD Day 1 is $490 million revenue for Microsoft once Sony's 30% cut is taken out. 6m of them going to Xbox in case of COD removal from PS is now $420 million but MS keeps 100% of that money. A deficit of only $70 million. However, say 3 million of those 6 million decide to get the game through Game Pass, and they're new Game Pass subscribers.
That is now an extra $540 million in GPU revenue thanks to COD, in addition to the $210 million from the other 3 million who don't sub but buy the game. Altogether that is $650 million in total revenue from COD (B2P, inclusion in GP), so MS actually make $160 million more in a COD withdrawal strategy off PlayStation, using the player numbers you gave in your example and assuming that a decent number of them would likely sub to Game Pass thanks to the game and keep their sub to play it online year-round plus whatever other games are in the service.