[bongoman37]

How is not giving personal information rude? He is just telling them the truth that they don't need that information which is correct. If a cashier were to ask you your bra size would you be okay with it? Why is it okay to ask for phone number which will give you all that and more.

[jraph]

politeness and truth are orthogonal concepts. You can be both right and rude. Watching the Big Bang Theory can provide a feel for this.

you can be both honest and polite.

Politeness is also relative to whom you are speaking to.