Why bother with a look-a-like? Salvia has many of the same effects and isn't illegal. THAT would have been something to bust the kops with.
I really think that the purpose of the staged drug house was to prove that their (crooked cops) false information was unfounded and unconstitutional. It would have been no different if somebody converted one room of their house as a winter garden. They could install heat lamps and artificial UV lamps and their thought is that these crooked investigators would use thermal imaging to create probable cause without ever going in the house or even walking around the neighborhood asking neighbors about suspicious activity. Just a guy who decided to grow a vegetable garden in his house and gets raided by a drug task force.
In other words they did NOT want anything that even remotely resembled pot for this particular operation.