"Sometimes port outputs can be programmed to show push-pull performance. Then, such a shortcut would surely result in a damage!" (my emphasis)

Not necessarily: according to your calculations for the 89LPC932 here, its output resistance could well be such that it could never exceed its Absolute Maximum source current rating.

Not that it makes this a good idea, of course; why would you want to try to drive a pin to a '1' when it is shorted to ground???