Anyone have any idea if an ICF wall form while laying flat (or on an incline) on its side while supported with shoring 16” on center can support the weight of a 200-300 lb man? 3-5 man crew? I ask because I have seen photos of ICF wall forms used for pitched roof designs but doubt that anyone would be brave enough to stand on a series of them laid out on an incline while they are NOT filled with concrete making it difficult to traverse the roof if the need arose during construction.

I don't think that would be much different than a wall form laying on a floor and stepping on it. Won't turn out well unless you can spread out the weight. The roof must be steep, or you would use a floor form, so build from the inside and fill from the top, with plywood to spread out the weight.