Halsin's fate isn't so important to the overall game. Sure, he has connection to Act2 but secondary at most.
I'm guessing you went into the warg pens far enough to trigger the event, but left. That way the default outcome played out.
Question but why couldn't Jaheira break the spoiler in Act 2, she's also a druid that's long lived like Halsin and she's literally right there.
