I think so, too. But I have issues with things like this, which may make him complicit. It seems they couldn't charge him with anything because of a conflict of interest with Darlie's lawyer, who was once (also) his lawyer:
"Also, at this time, Darin Routier admitted that he had looked for someone to burglarize the family home to benefit from an insurance scam, but that he planned to have the burglary occur when the family was not at home."
Darlie also made a comment about not being worried about finances after the boys' deaths because she was getting "$5000 for each of them" in insurance.
I think he wasn't charged with murder or as being an accomplice because the police didn't have any/enough evidence to make a case to stick. I think it was Darlie and her alone.
I recall something about the burglary scam too. He tried to hire someone to do it as I recall. Or he talked to someone about it. Something like that.