You do know that there was an already well studied global mass extinction, the P-T crisis, which is very well studied and clearly the result of volcanism?
I think you are exhibiting exactly the problem with the Alvarez hypothesis that makes people have such a gut reaction to it. It is a Deus Ex Machina that can be invoked at any time to explain a die off even in the face of conclusive evidence to the contrary.
If you haven’t read Extinction by Raup, I would encourage you to do so with an open mind.
Calling something that actually happened a “Deus Ex Machina” seems like a hint that you might not be coming to this conversation with the most objective mindset.
I think you are exhibiting exactly the problem with the Alvarez hypothesis that makes people have such a gut reaction to it. It is a Deus Ex Machina that can be invoked at any time to explain a die off even in the face of conclusive evidence to the contrary.