Would you argue that it is always better to assist one's xerox-sibs, than not?

My intention in offering those two "pathological" scenarios was to argue that there is an aspect of scenario-dependence in the general injunction "assist your xerox-sibs".

You've disposed of my two counterexamples with two separate counterarguments. However, you haven't offered an argument for scenario-INDEPENDENCE of the injunction.

Your last sentence contains very interesting guideline. I don't think it's really an analysis of the original statement, but that's a side question. I'll have to think about it some more.