Finnegan started his own performance shop thing a while back, meanwhile Frieberger has helped elevate Motortrend On Demand into a serious platform that recently got acquired by Discovery.
I think they are just more busy than having had a falling out. They simply aren’t enough to continue growing what they’ve started. The RoadKill + Mighty Car Mods episode was a year ago, and was Fantastic (and was the two of them).