He was able to deny the 3rd party push right before christmas so they could still sell XBS over the holidays, as much as they can to get inventory levels lower, but he knows they have to start publishing games soon. How long can you deny a thing when it's literally happening?
Why announce Blade, but not announce that it is exclusive? Why not confirm it's exclusive when asked? It's because by leaving in question what games will be exclusive or not, they can maintain the narrative in fanboy communities that there are still potential exclusives and thus value in owning an Xbox. Eventually, we'll hear that Blade is multiplatform, but the time between then and now, Xboxes can still sell and people aren't trading their Xboxes in.
The last thing Microsoft wants is people canceling Gamepass and trading their Series S and X back in to get PS5s only for people to buy 2nd hand Series S/X for pennies on the dollar, but have no interest to get GamePass because they're already cheap and don't spend money like that. A liquidation of the fanbase is entirely possible.