As has been said in other threads: If perks were for performance only, then why is the Ta-152 perked? The main arena environment takes her down well below her practical effective altitude. However because the aircraft was so rare, there is a perk in place.
So, if they establish that precedent, it only makes sense that rare birds like the N1K2 should be perked as well.
And, as a point of order, while the N1K2 may not contribute 50% of kills, there's a LOT of N1Ks in the arena (I encounter Georges almost as often as I do ElGay7's and Spixteens). Every N1K I run across is more than happy to HO.
Also: In a straight climb (no zoom) the N1K will out-climb the C-Hog to 10,000ft, in the altitude range where most fights take place. Turn radius is also superior flaps up and extended. Low-end acceleration is better (albeit by a slim margin). The Charlie is faster at max speed, (although at some altitudes not significantly so unless WEP is engaged) more durable and has better guns, though the N1K2 has more rounds in the clip. Based on performance, I would argue that a light perk roughly equivalent, if not slightly less, than the 1C would be appropriate for the N1K.
However, I'd be more interested to see how the N1K2's kill stats compare against the F4U-1C in the arenas NOW, rather than how the N1K2 today compares with the Charlie before the perk was added.