He's not arguing the position as correct because his dad told it to him. He's not arguing the belief at all, he's just stating it.

So no, it's not an argument from authority.

Given that he didn't provide any further evidence to his claim, I think it seems reasonable to guess that might have been an attempt.

More likely he wanted to share with us something his father had said that he felt was relevant.

Usually an argument from authority doesn't hold any weight, but come on.

It's their dad