Hi
I forgot to explain myself

From the point of view of the rules is ok for me. I think also the rules assume both effects (perhaps a little bit open to interpretations, also because of the name of the unit). I agree with you that is fair in balance-game terms.
My feeling was related with pure logic-simulation. What are loading the skeletons actually in the battle? It wasn't making sense to me. But I think this could be a good explanation of the rule: several lobbers of the unit are loaded with rocks, and others with skulls. An enemy unit receiving the attack will suffer losses from rocks, and survivors reatreating will suffer the biting.
Generally speaking, I like to learn the rules and try to apply it as best I can (mistakes are part of the learning process, and fun also).
Also I like to understand the reason of the rule, because it is easier to remember to apply it during the game, and understand the game mechanics. Sometimes a rule is just a rule (not only a simulation to represent certain units or effects in the battle) and its reason is to balance the game, or to keep it fun, no problem with that.
As a friend of mine says (not speaking about games): "Remember the rule it is not more importat than the reason it was created for"

Cheers!