” If you saw a yeshiva bachur dressed in uniform but doing something wrong, would you say its the uniform or their actions that are wrong?”
I think the point of the article was that it was a Kiddush Hashem because of how they were dressed they were easily recognizable as Jews. If they were dressed like everyone else, unrecognized as Jews, then they would be perceived as decent individuals, not too shabby, but not a Kiddush Hashem.