The main discussion thread is actually interesting as well. It provides plenty of examples of refusal-to-service in various fields, including:
- lawyers being refused services/rent because of the "higher risk of being sued"
- product-testing professionals being refused the sale of items that might come under scrutiny

Here, the question finds more interesting cases: on what basis should you have the right to refuse service? By doing so, could an entire class of citizens find themselves without homes, work, or medical services? As long as the discrimination isn't on the basis of gender, ethnicity, national origin, etc. then it's okay, right? For example, it'd be perfectly legal for businesses to only sell to blond-headed people. Doesn't it seem odd to restrict one thing, but not the other?