Is it okay to hate hate?

One of my Facebook friends recently posted about her mixed feelings on waiting on a customer who was covered in swastika tattoos. A back and forth ensued in which some folks said that it wasn't fair to make assumptions about the man - maybe he'd repented but kept the tats as a reminder; maybe he was Buddhist; maybe he had been forced to get the tats. Other people said that the symbol is inexorably tied to the Nazis and that a person who wears one is essentially embracing evil.
It took me back to my days working retail. I once carded a kid for a tobacco product, and he tried to prove he was of age by showing me his giant - nipples to navel - swastika tattoo (which was, as an aside, clearly a prison tat, which made sense because he also offered up the fact that he'd just left prison as proof he was 18). I asked the guy to close his shirt, which he wouldn't, and then the other girl I was working with kicked him out. The whole time this encounter is going on, he's telling us how this was an ancient symbol of good luck and doesn't necessarily make you a Nazi. I remember his friends dragging him out of the store as he shouted over his shoulder "I'm not a bad person!" 
For what it's worth, the guy gave me a vibe so evil that I'd wanted him out of the store before I even saw the tat. 
Anyway, the prison tat kid was right. The swastika is a very ancient symbol - according to Wikipedia, it appears in examples of proto-writing going back to the Neolithic era. It's very commonly found on artifacts from ancient India, and it is from Sanskrit that we get the word swastika which means, according to the Online Etymology Dictionary, being fortunate. It has been used as a lucky charm in Western society, a holy symbol in several Eastern and Western religions, a character in languages like Chinese and Japanese, a decoration in ancient Native American motifs, an emblem on coins such as those produced in 6th century Greece, and even a corporate logo in pre-WWII Ireland. 
So there's nothing inherently evil or violent about the symbol. The Nazis adopted it because they felt it was the symbol of the mythical Aryan race that supposedly had origins in Ancient India. 
All that being said, there's barely a shadow of a doubt that the nipples-to-navel kid wasn't a Buddhist. My Facebook friend essentially said the same of her swastika-covered customer. The swastikas associated with all those other faiths and cultures aren't all identical to the Nazi swastika - the arms are often fatter, thinner, curved, or set at a different angle. Many have designs in or around them. If you had a real, non-Nazi need to get swastika'ed, you could pretty easily come up with a design that didn't scream "I'm a Nazi and I'm okay."
In my opinion, proudly displaying a swastika tat is a tacit endorsement of everything the Nazis stood for; and more than that, it's a warning. Nazis didn't think that people like me and the folks I love deserved to live, and it's in my best interest to limit my interaction with them as much as possible. Honestly, the reason I asked the swastika kid to close his shirt rather than kicking him out of the store myself was that I was afraid. My coworker was Jewish, and it was her Jewish father who owned the store. And when my coworker told the guy she was Jewish, all I could think was that there was a hate crime coming on. I'm actually kind of surprised that the guy didn't retaliate.
What do you think, dear readers? If a swastika-sporter showed up in your place of business, would you serve them with a smile? Would you be wary? Would you give them the benefit of the doubt?