I believe the material is an abomination because we have seen, over and over again, people being addicted in some weird ways to these chemicals, and doing pretty loopy things.
Time and again, the Government has battled over the reasonable expectation of a retailer to engage in commerce over a "safe" consumer item, against public and police exasperation over the crimes committed, which legal highs have contributed to.
The Government lost patience with them in 2014, taking them all off the shelves until they could be proven safe. Now, they're coming back.
I am confident that "safe" doesn't mean safe at all. What a collection of supposedly benign chemicals will do on paper, and in a laboratory, or even with animals, doesn't mean a jot when introduced to an angry human being with a complex agenda and culture. I suspect we'll see these stores back, legal high-related crime will go up, and this stuff will be shelved, once and for all.