I reckon he was more likely a test subject for a new type of mind control. Maybe he just happened to take drugs anyways, and that was part of his lifestyle, and made him a perfect candidate for the test. We get these Zombie movies thrown in our faces so much, i always wondered if it was just a way of 'them' mocking how most of us already are, and how we think. Maybe its more than that, and its not enough turning us against each other in a 'dog eat dog' system, but 'they' actually plan on mind controlling a percentage of the population to actually want to attack and eat the rest. Hidden in plain sight and all that.
Just to add:- Most of these Bath Salts arent very physcoactive. A couple of the newer ones are, like the one closely related to Ketamine, but most are more like physical stimulants. (I dont know this from personal use btw)