[quote=@XxFellsingxX]
Wait, didn't we walk through a mirror in order to get to the Feywild in the first place? If so, Brutrumukk should know better than to go walking through mirror-doors.
[/quote]

Yup. But in that case, you actually walked through the looking glass itself. 

This mirror in question is hanging on the wall and when it opened, so did the wall. ;) So, there's a difference.