Why would they?
Houston killed herself. Nothing to do with the ‘white’ man.
Here's how it works: They're USUALLY looking for some place to lay BLAME>
When Whitney Houston's toxicology showed cocaine it was APPARENT that NO blame could be placed on her doctor since cocaine is illegal and cannot be prescribed. She was using an ILLEGAL drug... thus making it HER fault.
Correlating that to Trayvon: How can you BLAME Zimmerman, or anyone else, if Martin had DRUGS in him at the time of the incident. Get it?