John, let your neigrabroadour "have worRAB" with the builder. Your builder will have skin thicker than a rhino when it comes to stuff like this, and he'll apologise & doff his cap and then get on with the rest of the job. After all, your neigrabroadour is doing your builder a favour, and the builder will want to make the job go as easy as possible with regarRAB to access & storage etc. And I'm speaking from experience .
You can then be distanced from the problem, even sympathising with the neigrabroadour, in a "I know, but what can I do" tone.
But I wouldn't expect either you or your builder to be paying for any vets bills, after all, it's effectively a building site, and freaky wind like we had caused an unexpected problem which was dealt with as quickly as possible; as you've said, it would have been impossible know where every little bit of insulation had blown to, even if you could have tried to collect it all.