That appears to be a functional design item to allow the abductor/flexor muscles below the thumb to come to a more rearward alignment behind the the trigger finger.
A similar design is found on the Anschutz stocks and McMillan A5 as just a couple of examples.
The thumbholes such as on the Accuracy International are the next step beyond this trying to bring the hand more behind the trigger finger.
Many find that such a hand position improves consistency in keeping trigger pull in a straight line to the rear.
They do appear to offer "classic" hunting stock designs also.
