With many, many more hedge funds around, I don't think high short interest means what it used to mean...Shorts used to do painstaking work, now shorts read Herb Greenberg on the Street.com (note his asinine piece of work on HRB) and count that as due diligence.
With big cash flows, steady business (note this is rural and far steadier than other "comps" as 50% of the business is exclusives), this does not seem like an ideal short. Perhaps, some thing it is a repeat of Waste and its acq story from several years ago(although the story was completely different). Perhaps some don't like acq. strategy.
Is the basis for your strong sell simply because the short interest is back up to fall of 2002 levels? Perhaps your comment indicates that I am right-a new crop of naive investors who know little about a stock just pile on..
By the way, 11.8x eps...again, not terribly risky.