I reject the conclusion we have any responsibility or expectation to take this risk, completely and wholeheartedly.
There's no particular reason to think the Dragon will get back to Ziflin within the next hour, and we instructed them to stay well below the peak.
Furthermore, there can be no reasonable expectation that Mathilde can stop an Emperor Dragon doing whatever the hell it wants. No-one could have any expectations of that going in to Ziflin.
I think your assessment of the risk is also off, but as the outcome will as ever be decided by the dice. I just think the 'bad' range is very bad, and we're possibly more likely to see Bad than the usual risks we take. Diplomacy is an area of weakness, outside of select groups.
In quick order:
-We command the Throng of K8P. By choice.
We already put ten thousand dwarves in harms way in Ziflin. Denying responsibility doesn't make it stop existing.
If we didn't want the job we could have handed it over to Gunnars.
- The Dragon took several hours long with an intact, entrenched Clan Skyre that numbered tens of thousands and remained relatively fresh.
The combined forces of Mors and Eshin number less than twenty thousand, probably less than ten thousand.
They are exhausted after several hours of butchery to boot, the fortifications in Karag Yar have been trashed, and ammunition will be low.
This is not looking to be a long fight, unless someone has something like a Verminlord summoning scroll in their back pocket.
-If you think the Dragon is too indiscriminately homicidal to talk to in Karag Yar, a hold that is nowhere near it's lair and thus is of no immediate threat, I don't see why you think that staying below the peak in Ziflin, where the same Dragon just killed every Skaven will somehow convey some sort of immunity on the dwarven Throng we sent in there.
-There are no modern maps of Karag Ziflin.
None. Zilch. Not of the aboveground or belowground portions, because no one was going to risk feeding scouts into a mountain held by Eshin.
And this is further complicated by the fact that there is possible chemical warfare residue in much of the mountain, meaning that any attack is going to be slow and methodical so as not to get people poisoned unnecessarily.
I think you are going to be sadly disappointed if you expect them to be finished quickly like they were elsewhere.
-Nothing about stopping.
Everything about either talking it into a truce, or getting enough prewarning of it's attitudes to get out and withdraw our forces from Ziflin so they can bunker up against attack.
Mathilde literally wrote the book on Asarnil and his companion Dragon.
Uniquely among the current inhabitants of K8P, she has personal experience of dealing with an Old Dragon. There is a reason she ranks the dangers of this current situation as much preferable to attempting to talk to Black Hunger Skaven in an active warzone.