1. Phil is responsible for selling Xbox. You won't see him trashing the upcomming new iteration of the most important Xbox franchise. He personally is probably well aware of the visual issues of Halo Infinite and internally, he will probably have commented on it, but not as an outside facing figure. Similarly, you won't see major Nintendo or Sony execs publically trash upcomming Mario or Naughty Dog games for any fault they might personally see in the products. That is just unreasonable to expect and is in no way an indication of the exec's passion for games. Just look at the PS3 presentation at E3 2006, where everything was way below previously promised fidelity, the console ridiculously pricey (600€ in 2006 is the equivalent of 729€ today!) and trash presentations like the Genji presentation were given and how many big PlayStation execs at the time were dumping on that.
2. How did we see in Halo any failings of the CPU? PC scalability has included vast differences in CPU as well. I do agree that PC scalability is not a great example specifically because PCs are not dedicated hardware, but this in fact means that it is much more reasonable to expect scalability precisely because you do not need to accomodate for an absurd amount of cinfigurations. As long as there are only two possible configurations for Xbox Series, there are only three different configurations devleopers have to optimise towards: Xbox One, Xbox Series S and Xbox Series X. Presumably Series S is built in a way that scaling from Series X should be simple when reducing from 4k to 1080p res (I do not think it is quite as simple, but that is what Microsoft has claimed). In major engines you can request the specific system a game is running on, so you can, as a programmer, specifically change the assets you load, including models, the resolution you output at and the target resolution.