Higdon's and Hanson's marathon plans are great but unless he has a bunch of free time, it's going to be challenging to also layer on a 70.3 plan as prescribed. That's kinda making the rude assumption that he's the typical person I've encountered that just completed their first couple half-marathons and is looking for a new challenge - they normally underestimate the challenge of going from 4-5rpw to training 3 disciplines.
That aside, the simple
Matt Fitzgerald plan Triathlete magazine publishes is good enough to get to the finish. I personally use Joe Friel's plans loaded into TrainingPeaks and when training for a Full I pay for premium so I can track more metrics, rearrange WO if my work schedule gets demanding, etc.
