Going by the definition of hypomelanistic , itself, this guy would be just that.
hypo- or hyp-
A prefix that means "beneath" or "below," as in hypodermic, below the skin. It also means "less than normal," especially in medical terms like hypoglycemia.
Melanistic - black,
less then normal black in other words, that boa fits that desciption to a tee.
However, it remains to be seen if it is a genetic form of hypomelanism, or jst a hypo melanistic animal all to itself.
One thing for sure, it is a nice looking boa.
Besides the reduced black around the rings, its overall appearance, especialy on the sides looks to be hypo.
Im sure some folks would sell it is a hypo, ive seen far less hypo, sold as hypo.
Just my 2 pennies worth.

Mike