Bethany isn't going to like the fact that Galadriel is being locked up. However, she is not going to like the fact that people are playing around with dangerous magical things when they don't know what they do because clearly that's never gone wrong before ever.

She is not looking at Anders and Merrill. Not even a little bit.

So I think she wants to be part of the moderation crowd. Perhaps if the Wardens step in and offer a voice of reason - yes it is important to understand the rifts but perhaps this is something that can happen after they have taken out the extremely dangerous darkspawn magister.