I suppose it depends on the end goal and the whole diet. People into bodybuilding can be pretty obsessive about weighing their food and counting macros, and when you need X amount of protein but can only eat Y number of calories and fat, then there is not a lot of wiggle room for trimmings. It can be healthy if you follow a proper, whole-foods-based meal plan, but it doesn't sound like OP's future BIL is.
I haven't done bodybuilding for over 10 years, but I still follow the sport. Atm, I am doing body recomp, which is similar to, but not as extreme as, cutting. My macro targets are approx 150g protein, less than 100g of carbs, and as little fat as possible, with only "good" fats (nuts/seeds/oily fish).
Today's food was:
Whey protein shake with unsweetened soy milk, chia seeds, and a banana
Breakfast scramble for lunch (1 whole egg, 3 egg whites, 3oz lean ground turkey, 1 quarter red onion, and a decent handful of spinach)
200g chicken breast dry-fried in fresh, grated garlic, half a cauliflower, mashed with 30g of philly light and 2 roasted carrots and a protein yoghurt
Snack was 60g of cottage cheese, a handful of defrosted, frozen mixed berries, and a half a tablespoon of chopped almonds (approx 5 almonds) - sounds gross, but it is actually amazing and full of protein and calcium.
I think that's pretty healthy. I didn't do cardio today, but when I do, I have a raw fruit and nut bar for a pre-workout snack to fuel my workout.