Hi Walter,
First you are not required to walk the attic in the SOPs if you don’t see a safe way to walk. There are a few ways to tell what is under the insulation and everyone has their own way and reasons for walking or not walking the choice becomes yours only in the end as too how comfortable you are proceeding into the space.
You are required to disclose: how you viewed the Attic though so if you don’t walk it say how you observed it and why you did not walk it, that’s enough reason if you couldn’t see the joists because of the insulation to safely walk.