I was friends with Wesker; if there's one thing on this earth that I know about, it's revenge and how people get insanely hung up about it. And yeah, I bet if he knew about the volcano thing ahead of time, he would have pulled back.

[Though Wesker probably would have tried again later, but Birkin can't quite bring himself to say that. He's done so well making Giriko seem like a nice guy, and he's just not ready to deal with being wrong if that really is Giriko's plan of action.]

So yeah, that's a reasonable assumption to make.