For those not sure, the Goah Style isn't a copy of the Niko Style. The Niko Style was made by Gyuki's Grandpa and Kuroki's Master for the purpose of unifying the 'inside'. So the Niko style is descended from the Goah Style and Kawain Karate.
@KingRagnarok my guess is he can do a weaker version with his thumb that he saves for opponents that get too cautious of his legs, a secret stinger if you will.