Yes, it is cruel. But, its also a soemwhat realistic situation... Ahjussi is a socially aawkward person, he's poker faced, stoic, somewhat detached. He can be brutal too. He's trying to "act cool" and "keep his cards to himself". He's probably trying to get the upper hand before making his move, trying to get the information, test the waters... It's a defensive stance. It is cruel to Eui Joon, but I don't think he realises that.
