Well, hopefully the toxicology reports will help squelch the rumors.
My thinking is, Heath may well have used some drugs but if they were seriously interfering with his life then Christopher Nolan wouldn't have cast him. Nolan seems very professional and intent on making good movies, and I don't think he'd hand the fate of his big-budget movie over to a messed-up junkie.
Of course, you're right Marge, the average Joe doesn't even know who Christopher Nolan is, won't see his tribute piece, won't think things through to that extent. But screw the average Joe.