I'm with you; it does kind of sound like a drug-panic story.
The article does suggest that bombé is made from conventional drugs and basically cut with converter residue, so perhaps the residue slightly modifies its chemistry. Or it might do nothing at all; I'd be surprised if there's been a blind study comparing the effects of bombé made with cat residue to the same made with, say, clay.
I bet they just found a bunch of catalytic converter materials at the drug "lab" and jumped to conclusions. They are just having addicts steal the cats to pay for the drugs.
The article does suggest that bombé is made from conventional drugs and basically cut with converter residue, so perhaps the residue slightly modifies its chemistry. Or it might do nothing at all; I'd be surprised if there's been a blind study comparing the effects of bombé made with cat residue to the same made with, say, clay.