The words “killing” and “stone men” might be inaccurate. Unfortunately, researchers don’t seem to be sure about what exactly is going on in this passage. The key question is what or who the enigmatic “stone ones” are: the meaning of šūt abni remains unclear. In the Penguin edition, the translation “Stone Ones” is used. In other translations I have read “Stone Things” and “stone charms”, also other suggestions about what the šūt abni were have been made: stone splash-guards, stone anchors, stone sails, stone poles, stone kedge anchors, stone monuments, stone statues… However šūt seems to suggest a kind of living being rather than an object, while the act of “smashing” (not killing) seems to suggest an object rather than a living being. So the question about what the šūt abni are, remains unresolved.
But why does Gilgameš smash these šūt abni? The tenth tablet of the standard version, as quoted in your question, supposes Gilgameš smashed the Stone Ones “in his fury”. This emendation is based on a parallel passage in the fragments from the Old Babylonian Sippar tablet, where we are told explicitly that:
… And [the Stone Ones] he smashed in his fury.
And a little further:
The Stone Ones, O Gilgamesh, enabled my crossing,
for I must not touch the Waters of Death.
In your fury you have smashed them.
The Stone Ones were with me to take me across.
Anger seems to be Gilgameš’ main motive for smashing the šūt abni, a quite unsatisfying motive indeed: why is he so furious?
Personally, but this is nothing more than an opinion, I believe this kind of destructive behaviour could be explained by two reasons. Besides, the one does not exclude the other:
- Gilgameš is still the destructive tyrant, behaving like a “savage wild bull” of which the people complain to the gods in the first tablet of the standard version. He acts in fury, he fights before talking. And doing so, he makes life more difficult for himself and the people around him. This passage shows us Gilgameš has not yet reached his katharsis, he is not yet worthy of living the eternal life.
- We should also not forget Gilgameš is still mourning the loss of his best friend Enkidu. In the beginning of the tenth tablet, the tavern-keeper remarks that Gilgameš’ cheeks are hollow, his face is sunken, sorrow resides in his heart. These remarks are repeated by Ur-šanabi after Gilgameš smashed the šūt abni. A part of the problem seems to be that Gilgameš is not yet able to cope with his own feelings in a non-aggressive way.