The main reason I think he would have died first is that Warder's tend to become mad with grief but rather than seeking suicide, they tend to go out of control. I don't think it would be safe for Tomas to be feeling the loss of his bondmate around his family members.

Verin, on the other hand, would feel protracted grief, and would be able to deal with the emotion.

We saw Daigan earlier in the book, bedridden while she dealt with Eben's death; it struck me as similar to the pose Verin took towards the end of her talk with Egwene.