You are this mans personal trainer

You have been tasked with getting this man back to ottermode as quickly as possible. What routine / diet do you start him with?

I'll start - SS and GOMAD for a month. Move onto more complex foods and continue to increase calorie intake.

He doesn't need a personal trainer.

He needs a personal chef.

We all could use one desu

first i'd put him on a liquid diet of pureed fruits and veg, since severe starvation victims often cannot handle large amounts of solid food without intestinal damage.
once he's put on about 30-40lbs and gone back to solid food, i'd get him walking daily.
once his general fitness is up, bodyweight exercises until his joints, bones, and muscle can handle a higher load. then, i'd put him on a fullbody 2x a week, and up it to 3x a week after several weeks while doing daily walks.
once we're adding weight to the bar, cardio will go from walking to biking, running, or swimming.

he already is otter mode

5 subway full meals and some starbucks high carbonate drinks.

Zyklon B

9mm. he's never going to make it. spare him the pain and suffering

Literally SS+gomad