In what specific, concrete ways does it not work out the way you think it is intended?

> One way would be to say that all behavior "off the clock" and all attributes of a person not related to the job are protected. Another way would be to say nothing is protected.

Those are obviously potential rules, but I don't see that either of them is closer to any reasonable interpretation of the intended result that antidiscrimination laws are intended to serve.

I think we are starting to go in circles, but: It has the effect of cancelling out free discourse which is important to a functioning "democracy". A trivial example is that a business owner cannot be vocally anti-same sex marriage, because if she is, and a gay employee is fired for a "legitimate" reason, her behavior will go a long way towards convincing a jury.

Where this is going is why we are expanding the number of protected classes over time is that the real "intended result" is that you should not suffer at work for attributes that have nothing specifically to do with the job you are hired for.