I am not sure if I get you right. Manufacturing Ready is not the same as High Volume Production for all SKUs right? Manufacturing Ready is that they have all of the initial masks ready. When they start initial production(low volume) they address any bugs, and some SKUs like SPR took longer to get to High Volume Ramp Up due to many buggs.
So let's draw a line between the two. As I'm reading the slide + Ian's statements, "Manufacturing Ready" refers to HVM ready
for the process. But as you point out (and as SPR and the like show), just because the process is ready doesn't mean any particular chip is ready to be manufactured using it. In the case of Meteor Lake, they seem to be limited by the design/architecture more so than process.
Of course, there's definitely an "If a tree falls in the forest" kind of problem here. Intel can
claim the process is HVM ready, but we'll have no proof either way until/unless something actually ships using it.