Honestly, the bust probably had nothing to do - directly, at any rate - with the power bills these guys were racking up, assuming they were paying the utility bill on time. Power companies are in business to make money, and as long as they get their money when they want it, they're not going to ask questions or risk losing their income. The news article mentioned that neighbors noticed 'suspicious' activity at the homes of both these guys. Likely they aren't the brightest of people. Everyone I've ever known who got busted for growing did so through their own stupidity - loud music and/or other noise all hours of the day, traffic constantly coming and going from the home, telling people that they grow. It was probably the same with these guys.
I'm sure the police subpeona'd the local power company for their power bill records, just to add to their case against the two men to show how long they've been growing, which leads credence to any charges having to do with distribution, but not until after the bust, or at least while they were gathering evidence to go after the growers. It's highly unlikely the power bill led law enforcement to the homes.