First, the Bushido code was implemented during the Tokugawa Shogunate, a 250-year peace period, in an attempt to control the behavior of the Samurai, a highly trained fighting force with now no enemy to fight. It had no place during the Sengoku Jidai (Warring States Period). But I guess rape, pillaging and murder isn't acceptable if they're not in some far away land on campaign?
However, I find issue with karateka using the Samurai for marketing not for the hypocrisy of it (although that's a big factor), but rather the fact that it's historically incorrect. The Samurai had absolutely nothing to do with the development of karate! The Samurai were the military nobility of feudal Japan, the middle and upper echelons of the warrior class (abolished in 1868). Each clan had their own proud tradition of combat styles, and the history of koryu Japanese martial arts is well-documented. Jujutsu was the most common unarmed fighting style of the Samurai, one of 18 fighting disciplines (called the bugei juhappan) that they were expected to train in. Karate wasn't introduced to Japan until at least 1921, 53 years after the abolition of the Samurai class. But that doesn't mean that karate doesn't have a proud warrior history of its own.
How else do we know that Karate was not originally a civilian art? Prior to the Japanification (and degradation) of Karate, the art was heavily comprised of joint locks, manipulations and throwing techniques. This in and of itself is indicative of a combative background. Striking is not very effective against an armored opponent, but their joints are still exposed and dropping them on their head seems to work quite well. If you look at the unarmed fighting arts of every warrior culture, grappling has been the most prominent form of hand-to-hand fighting for the same reason. Strikes are used to set up the finishing technique, but are not finishing techniques themselves. This is also the same paradigm shift we see in Japanese Jujutsu. Prior to the Edo Period, striking comprised only a very small portion of the curriculum. But during the peace period, your opponents are no longer armored. We see the shift from a battlefield art to one of self protection all over the world, and Karate is no exception. The striking-based art that has grown to prominence is in reality a grappling style, the truth of which remains hidden in numerous kata.
So where did this myth of Karate being for peasants come from? As far as I can tell, it's due to the Japanese ignorance of the Okinawan caste system as well as the general view that Okinawans were an inferior race. Even their nobility were "peasants" compared to the "pure" Japanese. The Japanese had their own warrior traditions, so to acknowledge another culture having anything resembling an equivalent would be sacrilege. I'm pretty sure it's this same superiority complex that led to the Japanese invasion of most of Southeast Asia. When you associate karate with the Samurai, you're both continuing the rape and deletion of Okinawan heritage, and promoting the idea of a superior race. If you want to promote a warrior culture in your karate dojo, promote the Pechin. Educate your students and the public to the real history of the arts you teach instead of trying to capitalize on people's fantasies.
In all seriousness, at the end of the day this article is about respecting our own history, culture and heritage. Okinawan karate has its own, proud warrior history. You don't need to adopt the image of the Samurai to promote one. Besides, according to the internet cultural appropriation is frowned upon.