No, it isn't irrelevant. It clearly shows that vaccines are effective at reducing severe disease in an adjacent age group. In the absence of data for the 5-11 group, which is obviously not available due to the rollout just now starting, it's the most relevant data available. As it happens my son is 9.5 y.o. and the tallest in his class, so is bigger than many 10-11 year olds, and probably as big as some 12 year olds too. I have no reason to suspect a complete reversal of effectiveness between that and the empirical evidence I have provided. If you have some reason to think that severe disease rates will magically change to be worse for vacinated people sub 12, then by all means do share it.
Seems like I'm likely to stay convinced, as you haven't put up a skerrick of evidence to the contrary, and totally misrepresented the one thing you did post.Anyhow, I'm sure you are convinced you are doing the right thing for your family and community.