None of the action buttons are ever disabled e.g. if there is no shots left, the Fire button and hot key still remain so. That is the way that SSI designed the game, and its been like that for quite some time. And I think that you are the first one to ask for this feature since 1998 or whatever
.
It would be a non-trivial task to make the buttons active/passive depending on all the ifs and buts for each one. Basically because that was not deigned in from the start, so adding it might not even be doable.
I might have a look at it next year. But its highly unlikely to happen since it would be
at least a man-week of faffing about in the internals of the spaghetti, possibly 2 weeks.