...so we are saying that the person in charge of running security updates on production servers /is/ in a position to make a conscious decision on the (apparently now high) risk of installing what seems like a simple update, and possess the technical knowledge to figure out why suddenly nothing works anymore?...
I mean, this isn't even something they could easily undo: the old packages won't be able to be distributed anymore. They would either have to manually install the SDK themselves in a way compatible with the Ubuntu package distribution, or install OpenJDK and hope for the best (which, as you yourself point out, is unlikely to work, as there is likely a reason they installed the Sun JDK in the first place).
For sake of argument, I just tried to download 6.24-1build0.10.10.1 of sun-java6 for Natty from that website, and the site simply told me it, and all files related to it, were "(deleted)". (Which is so silly and obvious, I have to ask: was this a real suggestion, or are you just trolling me to waste my time checking? ;P)
Honestly: I have never known Ubuntu to keep an old package around. There was a new update released today, 6.26-2natty1, and the now hours old version 6.26-1natty1 is already marked: "removal requested in 16 hours". Do you have a more serious suggestion for how the old packages could be obtained?
That means they were deleted from the repository, but they are still archived in launchpad. The reason you don't see the files for 6.24-1build0.10.10.1 is because they were copied over from maverick. If you want the 6.24-1build0.10.10.1 files, you can get them here (click on the architecture you want to download under "Builds" on the top right):
sigh. I go to that URL, and under builds I click "maverick amd64". I then have to select which binary package I want. Let's select "sun-java6-bin 6.24-1build0.10.10.1", as that one will be most critical to someone trying to deal with their JVM disappearing.
At this point, you are presented with the "(deleted)" notice next to the file. In fact, along this path you have been presented with "(deleted)" next to every useful download (such as for sources); the only thing you can get is a 318.5 MiB diff from 6.22-0ubuntu1~10.10.
So no: old packages are /not/ archived in launchpad, and I feel you are just helping prove that. Accordingly, I will now reassert my question re wasting time. Seriously: this is ridiculous; are you even trying these links before claiming they work in specific ways?
I mean, this isn't even something they could easily undo: the old packages won't be able to be distributed anymore. They would either have to manually install the SDK themselves in a way compatible with the Ubuntu package distribution, or install OpenJDK and hope for the best (which, as you yourself point out, is unlikely to work, as there is likely a reason they installed the Sun JDK in the first place).