How are they gonna get screwed? Any simple background service would reveal the same thing and employers always do those... and nope, doesn't cross any constitutional lines, that's why he does it!
I think you're just mad because this Sheriff is doing his job, doing a damn good job of it, has his county's full support for over 15 years, and major respect from his deputies. When a SHERIFF has the respect of his deputies, that tells you something! The people like him because of the major decrease in crime in his county, as the criminals do NOT wanna go back to his jail and thus, they stay out of trouble!
MJ laws are bad in AZ, but tough shit, it's like that everywhere. Write the senators or whoever as the Sheriff doesn't make the laws!