Not trying to sound rude, but why high reps? interval Cardio yes
, as it should be less adaptive for the body compared to steady state, so the effects shouldn't taper off over time.
Hep rep stuff won't work too well. The person could still work in an 8-10 rep range, because if they go high rep, the weight used will either be too light, causing a pretty pointless effect, or practically to the max, just causing a Lactic Acid burn sensation and high rep stuff isn't necessarily a worthwhile thing and could make workouts take much longer, possibly leading in time to overtraining and mild associated side effects like reduced immune system, sleep issues, lethargy etc.
As muscle burns 45-50 calories for every additional lb, then going to around 80%-90% max weight for 8-10 reps, after an initial 4-6 week adjustment period to weights, will be beneficial I feel and as long as the person doesn't eat 3,000+ calories a day, with a fairly chunky Protein intake per day, they should get a desirable amount of caloric intake, to stimulate sensible weekly fat loss amounts, (1-4lbs, weight dictating somewhat), but not a lot of muscle gain, if the individual doesn't want to end up looking too athletic, or bulky.
So I agree in part with what you said, but respectfully not in whole
I really do appreciate your attempts to help people and I hope you will stick around, because you seem like a superb person and your personality type is always very welcome here
Best wishes to you and welcome.