In what way is it bad advice? To me it makes complete sense. Much of the time when we feel "hunger" we are really just thirsty, so taking a sip of water can be all it takes to satisfy a craving, and stave off snacking. Likewise fruit and nuts are much more healthy than junkfood. So if eating fruit or nuts prevents him from eating junkfood then it is a benefit.

My body fat % is extremely low, but I can't remember the exact number. When I do those electric handheld fat % tests, they error out. I'm an archetypal tall and skinny nerd, basically.

The system works for me because I end up satisfying the craving on healthy stuff before I can get to the unhealthy a lot of the time. That said, everything I write about is based on personal experience and I just try to distill some of the general tips that anyone could use.