I've never heard Nic play so can't comment but here's clawhammer banjo and YOU decide if there's a likeness:

So the hand is a relaxed claw shape that never alters. The pointer or middle finger (player's choice) strikes the 3rd string, followed by a brush down across the lower 2 or 3 strings, ending with the thumb plucking the 5th string.
Now, after striking the 3rd string, the pointer or middle will often hit the head, and the hand motion is like knocking at a door..

Hope this is helpful.

Cheers
Fred