Stern has left the rule open to his interpretation. I don't think anyone but Horry gets suspended based on the many ways one can interpret the exact rule.
The rule states the player can't leave the vicinity of the bench during an altercation. Well if you look at the definitions of those two words there is a lot of ambiguity there. Stern is giving the league an out.
The true definition of an altercation, yes I looked it up, is:
Main Entry: al·ter·ca·tion
Pronunciation: "ol-t&r-'kA-sh&n
Function: noun
: a noisy heated angry dispute; also : noisy controversy
synonym see QUARREL
Main Entry: vi·cin·i·ty
Pronunciation: v&-'si-n&-tE
Function: noun
Inflected Form(s): plural -ties
Etymology: Middle French vicinité, from Latin vicinitat-, vicinitas, from vicinus neighboring, from vicus row of houses, village; akin to Gothic weihs village, Old Church Slavic visi, Greek oikos, oikia house
1 : the quality or state of being near : PROXIMITY
2 : a surrounding area or district : NEIGHBORHOOD
3 : NEIGHBORHOOD 3b