They aren't using the word in the medical sense. "Devised, arranged, or fabricated for special situations to imitate or replace usual realities." The product is made to look like ganja and to be used as an alternative to ganja. s_baby points out the correct term is analog.

>> the proper terminology is "synthetic cannabinoid."

For the cannabinoids themselves, certainly. Now, what's a good way to refer to the products that are sold in head shops and all sorts of other places? They are a blend of plant materials laced with a one or more synthetic cannabinoids.

Synthetic cannabis does not seem wrong here.