Both a 3-day fullbody and a 4-day split are good options, assuming that it's a GOOD fullbody or a GOOD split.
Just to clarify, what are his goals? I know this is the weight loss section, and he's pretty big as is, so fat loss seems the most obvious goal, but since it hasn't been stated, it's hard to give more than just general advice.
Another thing to consider, when you're after results, you should consider someone a beginner or intermediate based on their ability to recover from training and progress, rather than based on how long they've been training for or what cool tricks they can do with a barbell. Beginners can make really rapid progress, and a good beginner program will make use of this. More advanced lifters progress at a slower rate (which is why going from a 600lb squat to a 610lb squat is a big deal, while going from a 60lb squat to a 70lb squat really just requires squatting on two seperate days), and their programs are designed to best achieve whatever limited gains they can make. So, whatever program he uses, make sure it's something suited to his ability to make progress.
If he's going to do cardio and ab work, best bet is to do it immediately after strength training. There's no set time period in which someone should change intensity. As a beginner, the goal in the gym should simply be to lift more weight, or to lift the same weight more times, every time you enter the gym. When you can't do it any more, you deload (take the working weight down 10-20%), then start piling the weight back on over the next few weeks and try to beat your previous sticking point. When this method no longer yields further results, it's time to move into intermediate level programming, in which you play around with volume, frequency, intensity and recovery to get to a point where you're getting stronger once again.
Sorry if this gives you more questions than it answers, but without knowing more details about his training history, what exact programs he's looking at, etc, it's hard to give more a specific answer than this.