Not at the extreme ends it's not. He's a person for whom at a borderline weight a healthcare professional would probably be wise to look at his lifestyle holistically and make a judgement call. BMI is a great indicator for people who fall into the normal distribution, but at the tail ends there is certainly a little more leeway.  I think it's fair to say 6'7" is way above a normal range of heights, therefore a reasonable assumption would be that less data exists for exact parameters of ideal weight. If I was his doctor I think I'd be ok with that weight, coupled with his reporting of improved diet and increased activity. As long as he keeps it up that is. He could probably now do with eating more protein and doing some weight training now.