All this is about is book-keeping. Installing a Slackware package
as Slackware package means that there is absolutely no record of
what you have done; if, for example, it overwrites an important
file, it will be *very* hard to find out.
That's how this started.
But, this business about the install script not running (the
administrator wanted to skip the slackware install entirely and some
script didn't get renamed to fit with the debian naming convention for
the post-install script) implies that the focus has shifted to
efficient mass-installation of slackware packages.
If all you want to do is register the binaries, that script is fine.
If it's a but that that script doesn't create an package which
automatically runs the post install script, people are thinking that
slackware packages should be trivial to install on debian systems.
Once more: if all this is is bookkeeping then the slackware install
script is a non-issue. If this is about creating valid debian
packages then there's a lot more to it than just the slackware install