Now that makes me wonder, why so very different values amongst
the brothers? But I believe that Liam had the best interests of his brother in mind, as well as thinking that he may be making. a joke at the expense of the young couple. Now put into context it is easier to understand.
Knowing the backstory from Parts One and Two of Book One would also help. Liam was one of the brothers who were forced to marry because they'd gotten their girlfriends pregnant. In that respect, he was trying to help his little brother not make the same mistakes he made. But that doesn't detract from him being a cockroach. Liam's not just the bad boy you love to hate. He's borderline evil. That will come out more as the story progresses.