Sadly this doesn't happen sometimes as people still don't upgrade, but most do which is fine for me. I hope it stays that way.
As for crashes, that's pretty bad to be sure, but I didn't see the OP try filling a bug-report.
1. Violation of stated policies
If you tell me I can disable updating and then update anyway, I have been lied to. A promise was broken, an expectation violated. It is totally reasonable for him to be upset about this.
2. The excessive harassment of a tiny minority of users.
Several people in this thread have lauded the default nature of Chrome updates, and they're right! But it is that very default which makes the harassing banners and warnings all the more pernicious. Who is google bothering? The 99% of users we (as developers) care about and who haven't gone to great lengths to disable auto updating? No, they are only bothering the tech savvy, persistent, already annoyed user.
This is simply not where the burden of support comes from. As an anecdote the company I work for recently received a complaint that our website wasn't rendering properly. On investigation it turned out the user was trying to browse in lynx! While we're obviously disappointed that wordpress isn't lynx friendly we are going to spend 0 minutes trying to fix that.
I don't think they told him anything -- he just used an unofficial method to stop it that worked before, and then they changed it.