Your article on this topic suggested fiberglass insulation as one wrapping material. I wouldn't advise this for a couple of reasons. It can be a breathing hazard if not handled properly and it can also be damaging to the skin.
Wrapping a Fig Tree
Certified GKH Gardening Expert
We agree fiberglass insulation would not be recommended. The article suggest several options and plastic insulation is one of the possible choices listed.
This could be the insulation foam boards that are available, cut to form a protective home around the Fig Tree.