If he was overwhelmed with his own celebrity at the time, as Bill Hader seemingly implied, it would be somewhat understandable.
In the sense that relatively few people achieve Bieber’s household name status, and he did it as he was traversing through his teens and into adulthood, which is generally an emotionally tumultuous period for anyone.
To be sure, being Bieber-famous doesn’t excuse anyone from being pompous and troublesome on the set of a network sketch series, and it’s interesting to hear Hader reflect on it a little less antagonistically five years after the fact.
Justin Bieber took the Saturday Night Live stage as host back in February 2013, which was during the height of his ongoing mega-fame, and a year before he started getting in legal troubles for DUIs and a variety of other infractions.