Yeah...it's not even about recognizing him...his master would destroy him if they fought hahaha 100% sure it's not him.
It's probably another disciple or someone who learnt it somehow
At everyone asking about if he is his master the answer is no. When the dad meets Noya (sp), Noya reminisce talking with the Master. Master taught him the same way he was taught, one disciple. I’ll dig for more info in a bit.