It comes down to whether or not the Stingray evidence was the only thing against him... if everything hinged on that evidence being admitted, then he'd be smart to push it to the end. However, if there was anything completely outside the Stingray evidence, the plea bargain is the smart choice.
I completely understand him taking it, but I sure wish he would have pressed it. If it had been pushed earlier, I'd have suggested starting a GoFundMe or something for the guy to fight it and force the prosecution to show the Stingray. What's 4 years in prison worth? (although you can't profit from your crimes... not sure how that would work legally, but it'd be worth trying to get this out in the open).