I don't think that is really the point that was being made. As you say the practical chances of google storing this data for x years, then committing corporate suicide by decrypting it is are miniscule (and presumably apple agrees).
The point is that there are layers of security, and by moving the data outside of their physical control apple has given up one of those layers of security.
I'm not sure why people are are thinking in such a limited fashion. Google is effectively holding onto the data for the US government or whoever else has the capability to access all that data in the future. This is the kind of stuff authoritarian governments dream about. And I'm not saying Google is doing it intentionally, just that they're holding onto the data at all and at some point there will be somebody who will make use of that data.
If that is the argument, does it matter whether it is Apple or Google who is holding the physical data? Apple and Google are both based in the US and beholden to the US government, so from the government's perspective it's just a change of address when they send out a warrant.
It doesn't. I'm not sure why you think I think there's a difference. Any corporation that stores our data long-term is a threat to our privacy and our rights.
> does it matter whether it is Apple or Google who is holding the physical data?
It might matter, yes. A company run by a guy like Eric Schmidt is a lot more likely to play nice with the US government when it comes to privacy compared to a company run by a guy like Cook, who from the outside seems obsessed with user-privacy (as long as China isn't directly involved).
Of course, just wanted to say that not two big US companies are the same, it highly depends on who leads them. The powers that be that decided that a guy like Schmidt was fit to run a company like Google could do that again.
The point is that there are layers of security, and by moving the data outside of their physical control apple has given up one of those layers of security.