Who really believes the mirror tale anymore?
The Hubble's mirror was the 11th made. You're really telling me that Lockheed (hmmm, that name rings a bell) built 10 mirrors then screwed up the 11th? Or did the NSA tell Lockheed "just muck it up a little bit, we don't want people to figure out how powerful Keyholes 1 to 10 really are. Those astro-boffin dome-heads won't notice" Occam's razor - sudden error on critical spacecraft component or deliberate mistake? This doesn't take a huge conspiracy either, just a few key people at LH & NSA.
Secondly: "parts of the massive instrument will survive the trip back through Earth's atmosphere and could fall on populated areas" Oh, yeah sure. The Columbia broke up and scattered itself over some very heavily populated areas, and no-one was killed or injured. Plenty of spacecraft have come down over populated areas (there's even a chunk of Soviet spacecraft that landed on Sydney in the Powerhouse Museum) and there is not a single case of anyone being hit. The chances of damage are astronomically (hah!) low. However the chances of someone getting their hands on some of the kit from a Keyhole Spy Satelite? Ah, well, of course THAT is the real problem isn't it?
It is so bloody sad that we have pretty much had single-figure numbers of actually useful space-science telescopes, while there are hundreds of warmongering spy sats of far greater power up there, at hundreds of times the cost, while science has to beg and plead for the tiniest scrap of funding.
Little wonder The Culture aren't interested in Contacting us, we would ruin the party. We really don't deserve to survive as a species. (I might have been reading some Stephen Baxter lately, yes)