Ummmm but, no matter the language in the will,
at law, it's only a statement of preference.
It cannot bind the executor, and does not bind the nominated guardian.
So, yes, a will is not just about property as you asserted earlier...
Also, a nominated guardian will have an effect until or unless a court overturns it. It would very odd if the nominated guardian would not have been consulted and agreed with their role as such should it be needed prior to the inclusion in a will.