[Trespasser Spoilers]Agreeing with Solas? Somewhat confused.

Basically, if your Inquisitor romanced Solas, one of the dialogue options you have when you meet him again at the end of Trespasser is to basically just agree with him and ask to help. He denies you, but the fact still remains that you're effectively saying that you support what he's trying to do.

So why would she then turn around and try to change his mind/stop him, and go back to warn everyone else about what he's planning to do? I mean obviously the answer is that it's setting up the baseline for the next game, but if they didn't want an "inquisitor supports Solas" variant of whatever the next game ends up being, why did they bother putting in that dialogue in the first place?

Am I being stupid and not understanding what's going on, did BioWare just overlook that, or is the answer something else entirely?