Phil is doing his job. You can't fault him for what he said.
It is worth noting that being sold out is a bit of a nebulous statement. How many units does that comprise? If the rumors of PS5 outselling XSX+XSS at 3:1 combined is true, then that's a deficit that's hard to overcome. Worse yet, if that deficit is faced in your best regions, because it gives your competition a substantial global userbase advantage. That has a knock-on effect on the competition's ability to secure further exclusives, as they have a larger installed base, which then gives them an advantage in growing that base even more.
GP and a power advantage didn't help X1X very much, as it faced a userbase disadvantage, and an ongoing impression that the console lacked games. Exclusives are really important, as they represent the differentiator in gaming libraries. You're not overcoming a deficit by saying, "yeah, we have everything the other guy has, except their popular franchises." You have to leverage your heavy hitters too. Halo still has mindshare, even if it lacks the same market punch if once had.
It was really important to come out the gates with that familiar brand on the console. Whether it sold additional units or not is immaterial. It's about setting a good first impression, particularly if your competition has a production advantage over you. It can keep some of those thirsty casuals on the fence while you ramp things up.