Big jumps usually cause trouble for a week or two. Sounds like he's already pretty fit and active, so no need to rush the dose escalation. Dude's crushing it with the exercise routine.
Mayo guidelines say point-eight per kilogram if sedentary, one-point-one to one-point-five if you're active. One-point-seven's the ceiling for serious athletes. They also note that people carrying extra weight should get their protein targets from a nutritionist. I've always leaned toward that...