Yea, if you refuse service to any group based on race, age, or sex, it's discrimination and it's against the law. The law is in place BECAUSE there are people in our society who don't see other as equal. That's the point.
I don't think that law should exist. You should be able to do what you want with your business. You don't like certain people, no one should force you to have to do business with them, no matter how ridiculous or ignorant your reason may be.
I am 100 percent against any law which tells someone they can't make a business decision because of someone's race, ethnicity, belief, gender, or whatever.
Besides this, many businesses already take part in very similar practices.
Ever hear of "ladies night" at the bar, where women get in free but men have to pay? That's discriminatory practices, but I do not know of anyone who has filed a lawsuit over it. Technically, the men shouldn't have to pay to have the same service as women based simply on the fact that they are a man, but yet it happens all the time.
How about discounts for "senior citizens"? They should be illegal because they discriminate against younger people based on nothing but their age.
If you think either of these is okay, imagine if it were about race instead of gender or age. Maybe at the bar it's called "white night" and white people get in free but everyone else has to pay, and see how long you think that would take to see a lawsuit and national news coverage. Imagine if white people got a discount but everyone else had to pay regular price.
Really the only thing it's about is whether or not people make an issue of it and can get the backing of the popular culture, as I illustrated directly above. When it's about gender discrimination or age discrimination, few people seem to care but when it's about race everyone goes crazy.
Face it: Discrimination runs rampant in America and everyone turns a blind eye unless it's about a hot button issue like race or homosexuality.