I think, their strategy is actually the reverse. They try to strengthen XBOX by making this game a quasi-exclusive for it.
I don't think, they'll gain many new XBOX customers with Starfield, as it's neither so exceptionally good, nor does it do things, you can't find in other games, to make anyone buy a new console for it.
But since their other big IP this year, Redfall, was a complete dud, they're probably rather even worried of losing long-time customers.
AMD might have had a surge in component sales due to Starfield bundles. But I can't see it selling a lot of Xbox consoles when it's a game that kind of makes the console look bad with a 30fps cap even on the top-of-the-range variant.