If I may.
Your justifications are...
Insufficient.

Just because one of the most magically inclined races lacks magical capability or much in terms of intelligence does not mean that they gain physical attributes as a compensation.
Genetics and evolution doesn't work like that.
Even freaks of nature aren't grossly over tall as your character, even of they were they wouldn't be better for it.
Constant joint pain, stretched muscles, atrophy, brittle bones, and many other physical ailments would afflict your character for being the height he is.

You think even in life that those who are 7 foot tall are like that without consequence?