This stuff looks to be much like the composite decking materials.
If that's true and all else being equal (cross section profile, size etc) this material will support ~ 1/20th the load than its equivalent in Aluminium. AL. modulus is 10 million psi. The composite wood/plastic materials are around 400-500 thousand psi.
I also suspect it might move a bit in use much as wood or the composite decking does..
Neat idea though..