Bullshit. They still got a portion of game pass dollars, season passes, all the game's overpriced mtx, and had a player base strong enough to keep people pumping money into that mtx. The $300 is fictional math most likely assumes everyone who played it on game pass would have bought it instead, because that is how those kinds of estimates work.
If anything they can acknowledge that game pass does eat into individual game sales, but wasn't that supposed to be a loss leader kind of thing?