Amazon is down with the sickness
This is an easy one folks: Discrimination based on self selected traits (like, say, being a Nazi or a Catholic or a Bucks fan (sing along: one-of-these-things-is-not-like-the-other)) is generally ok, and even a good idea. If someone tells you they believe something, its usually best to believe them and make judgements based on their statements.
Discrimination based on born traits, like homosexuality or skin color or even, to an extent, nationality (in so much as nationality is a choice for the individual in question) is not ok.
Was that hard?
Here's an example sure to singe the eyebrows of most people:
If someone is a zionist radical, its ok to discriminate based on that information.
If someone is a Jew, its not ok to discriminate based on that information.
See the difference? One is an ideology, the other is just some category assigned by a third person (and often these categories we use, like skin color or whatever, have very loose boundaries).
To sum up: Fuck you Amazon.com, unless you recant your homophobia I'm done with you.