My players didn't accept the deal with Talis

Or rather, the walked in dressed up as cultists, were greeted by Talis mistaking them as such and inviting them to dine with her as she was expecting some fellow conspirators... and procedeed to blind and silence her first round of combat. That's where we left off, and I had the whole "Talis asks them to go against Rezmir in Skyreach + uses a whistle to call wyverns for the party to ride to get to Skyreach" etc etc thing planned. I got most of my ideas from here so you might actually know. I had a discussion with my players after the session as they've been extremely out of it lately which led to generally poor (and extremely out of character) decisions on their part in these last sessions, this being one of many. I hinted that had they not fought her right away she would've been useful and we agreed that I should stop always letting them win and they should suffer the consequences of their actions a little more. But what would they be in this case? Surely they won't have wyverns nor the banner. They know they're supposed to go to Parnast but they don't know about Skyreach. What else is in store for them? I want them to notice things would've been easier with Talis on their side, but also I don't want to punish them too harshly either. Maybe they have to get there on foot which means the castle is already up in the sky when they arrive AND they have no mount? Any other idea?