I am not a Roon employee. But my guess is that it is a standard suggestion that will work for all the suggested NUCs. That doesn’t mean that a particular NUC/motherboard can’t use higher rated RAM.
But, as things go, I always go with the RAM as suggested by that manufacturer for that motherboard.
I have a very similar NUC which I use as a ROCK core - the NUC11TNKv7. Same generation, almost identical specs.
I use two sticks of DDR4-3200. Works fine.
I see that same memory specified on Intel’s page - it’s probably the same page you’re looking at. Strongly recommend you go with Intel and @Rugby’s recommendation.