Isn't Hubble in hand is worth more than a possibly lost shuttle?

If I understood O'Keefe correctly, he says we should let Hubble rot
because it would be too risky to send another mission there. That
doesn't make sense on many levels (like past missions for example),
but I want to discuss something else here.

If we can ask 25 year olds to risk their life in battle (Irak or
elsewhere) for whatever reason, why can't we ask 40+ year olds to do
the same for science. Clearly they would be willing (at least some of
them, I suspect all of them).

If America as a nation can spend dozens of billions of dollars on a
project, but can't "take risks" with peoples lives for exploration,
then it is probably finished as far as human exploration goes. Or is
it just that O'Keefe has a problem here?

And what about these human trips to Moon or Mars anyway? I bet that
they will be a lot risker then matching Hubble's Orbit and bolting a
few new pieces on to it.

There might be other good reasons to trash Hubble, but I think the
reason O'Keefe gave is surious (to put it politely).

What do you think?