Ooh, nice. Muffet has heard from other people about their experiences with people turning up from different times and/or different versions of their own worlds, and is beginning to suspect that a lot more went on in her world than she remembers, so if she and Asgore wind up getting past the awkwardness long enough to compare notes on their respective timelines she'll be very interested in this.

Also she'll be genuinely happy to hear about him coming up with a different plan. Would've been nice if he'd done that before six people died, but it's still progress and she figures she can't judge him too hard since that's Sans' job she did also try to kill Frisk during their journey.