Justin enjoyed the time he had to spend with Sam even if he was tired from traveling. Aside from Emily, she was his best friend and it had been a while since they were able to hang out. Though they didn't get to do much hanging out when Ellie was awake since she demanded constant attention.
He knew that having two kids under the age of three at once would be extremely taxing but it would also make things easier in the long run. Siblings could help keep each other entertained once whatever new baby they had was old enough.
Goodness knows he had seen that with his cousins growing up. He probably would have spent a lot less time in his room if he had siblings from a young age too.