It's no more absurd than pointing out that the whole "red state/blue state" dichotomy is backwards, because Republicans should be blue because their "blue blooded, hoy-foloy uber-rich", and the Democrats should be red because they're all basically closet communists. Neither of these generalized stereotypes are even remotely true.
I have to say it again, that "sinister" originally just meant "left", as in direction or physical orientation. In heraldry, 'a lion, sinister' means a lion facing to the left side of the coat of arms, not that the lion is evil or anything. The alternative meaning of "sinister" that you are referring to, is again a definition added by people who wanted to put forth the ridiculous notion that left-handed people are evil and not to be trusted.
But you can read into it what you want. If you're worried that some people might take my ironic wordplay too seriously, maybe the problem isn't with the ironic wordplay. Stereotypes, unfair as they are, exist for a reason, I don't know what to tell you. Maybe it's healthy to utilize properly measured footwear.