2) Nothing is free if you are buying more hardware. Considering the costs of supporting Chrome/Firefox are very incremental, doing anything other than running the browser natively increases time and cost.
3) Cheap yes, but you have to do it, and its not like buying one piece of hardware. You have to do it for every person. Better, but not great. No one likes running VMs on their boxes because it still crawls, even with 2 cores and 8GB ram.
4) Don't disagree with you at all. I was against this design decision from the beginning but lost that battle. It doesn't change the fact that we need to test all of it.
2) The hardware issue was addressed in 3. Also, I don't follow, what do you mean by "the costs of supporting Chrome/Firefox are very incremental?"
3) That's a fallacy, actually. You're both proposing and confirming that "No one likes running VMs on their boxes because it still crawls". I, for one, run Windows XP VMs on my 4GB Core i3 iMac with no burden on the host OS at all. Some people might suffer with it? Yes, but some people could try tuning their setup for their needs.
Anyhow, we both know that the kernel of your argument is the first topic. I could convince you that the benefits outweigh the costs in 2, 3 and 4. But if your mindset is focused on giving the very same experience to every agent that can reach your app, or giving no experience at all; this argument is already over.
Also, saying that Apple does X or Y means absolutely nothing. Even if your company were almost exactly the same as Apple in every competitive aspect, nothing can assure that copying its culture would also lead you to a successful path. Actually, I believe history tells us the opposite.