Re: testing & stable: vanished packages?

[furufuru@ccsr.u-tokyo.ac.jp]

Antony Gelberg wrote:
[...]
> apcalc isn't in testing as it has an RC bug (read: serious problem).
>
> http://bjorn.haxx.se/debian/testing.pl?package=apcalc

Thanks for the info!  This webpage
(entitled "Why is package X not in testing yet?")
seems very useful.

But, why then isn't the older package (which is part of the stable
distribution) kept for the testing distribution?  As I said,
it _appears_ to be working on my etch box.  Is it known to be seriously
broken on the etch platform?  Or, does this phrase in the webpage above

    apcalc has no old version in testing (trying to add, not update)

mean that the package maintainer intends to re-introduce the older
package while the bug in the newer is being fixed?

It seems that I don't quite understand the process in which packages
are updated.

Regards,
Ryo