This is a common misconception, probably due to the unfortunate naming. Expert layers are not "expert" at any particular subject, and active-size only refers to the activated layers per token. You'd still need all (or most of all) the layers for any particular query, even if some layers have a very low chance of being activated.
All in all, you'd be better off with lazy loading the entire model, at least you'd know you have the capability to run inference from then on.