Just some thoughts:
Read the new Dave Tate article, it will provide motivation
HIIT and fasted cardio will be good after walking is easy and he wants something more
Leg press - better than ham curl/quad ext.
Cable pull-throughs (hits the hams well)
Good mornings (excellent choice, and he can work on his range of motion in the exercise as an indicator of improvement in ROM/flexibility as well)
Bodyweight lunges if possible, "static" then dynamic then walking eventually.
I don't even think I'd mess with bench press yet honestly, just overhead press for a while, and standing at that. I'm thinking of COMPOUND exercises, and bench almost seems too isolated for this guy at this point, standing OHP will hit the core and probably burn more calories.
Bent-over rows and weight-assisted pull-ups/dips are perfect.
First few months:
-Some light cardio (cycling, swimming)
-2-3 full body workouts
Next few months:
-3 sessions fasted cardio per week (still walking for the most part)
-3 full body workouts per week
-1 session HIIT (probably on a stationary bike)
-Walking as preferred
-Fasted cardio when possible if it has proven successful and he likes it*
-3-4 full body workouts (clearly he isn't going to be doing any failure work!)
-3 sessions HIIT, adjust with fasted cardio, do at least 5 combined...2 sessions fasted cardio, 3 HIIT, 4 HIIT 1 fasted cardio, and so on
-Walking as preferred, it's still convenient and enjoyable even if there are more effective methods
Here's a little program that shouldn't be too hard:
Full body 1
Cable pull-throughs 4x12
Stiff-legged deadlifts (start light and teach the movement, shouldn't be overly challenging) 4x10
Overhead press 4x8
Assisted pull-ups or machine/cable pull-downs 4x8
Full body 2
Good mornings 4
BW lunges 3x15 or work up if 15 aren't possible, when 15 static lunges are possible go up to 15 dynamic, 15 dynamic to 15 walking, then add weight
Assisted dips or if these aren't possible, light bench press DB or BB 4x8-10
Light-weight bent-over rows - if they're uncomfortable, machine rows or horizontal cable rows 4x12
Hope you find some of this useful.