What could be the reason for his return and what can be done to manage such situation?
Generally, everyone has their own reasons for returning to gambling after a break. If they previously stopped because they were busy with work and didn't have time to enjoy gambling, then when they have free time, they can return to gambling without any problems. I see people like this as responsible gamblers, of course only if they gamble just to enjoy free time and have fun. Moreover, situations like the one above are not always a problem, especially for those who are responsible gamblers.