Child growth chart question

Ok so I don't really expect to get someone who knows to respond but here goes.

Normal sized child at birth. Healthy. 21.5" 8pds 3 oz.Male

Normal growth during the first year and then deceleration.

Normal height gains at above average but not extreme rate, is 47" at 6th birthday. (properly measured, barefoot)

Weight gains have been off bmi charts, which seems to matter to some people. Weight gain has been constant for three years, at rate of 10 pds/yr.

30 pds at 3
40 at 4
50 at 5
60 at 6

That's upper 90's percentile.

Here's the thing, he's not chubby. He has a very high metabolism and it's muscle weight. No body fat hardly, extremely "cut".

Zero weight training (obviously, he's 6)
Lots of muscle development and definition. Very strong.

Some in the medical field would say he is obese and "at risk". I think they are wrong. Are they?

Bonus question. The father is 5'10 and the mother is 5'6". Usually a child falls within natural ranges of the parents but there are exceptions to the rule. Project the height/weight at 18.