[Jedd]

I can appreciate the frustration.

I imagine some atheists may be frustrated to be told that they're not as nice (charitable) because of their rationality.

In any case, to your question 'who cares why someone is charitable?' I'd suggest that it's important if your definition of charity is something along the lines of a voluntary offer of assistance.

If you're coerced into providing assistance -- either by promises of eternal happiness, or threats of eternal suffering -- then it's not so much charity as taxation, or perhaps a promise of remuneration.