No. Jesse Owens was reasonably popular among Berliners and many German athletes, such as Luz Long, first off, so you wouldn't be alone. Secondly, the government wants to look good for the world and impress London in particular. Carl von Ossietzky is still in the news after being transferred from a camp to a Berlin hospital, and the government isn't eager to create more causes celebre. Streicher's publications have been banned from Berlin for the summer.

So long as you aren't openly leading demonstrations against the Nazis or publicly embarrassing them beyond a reasonable limit, they'll leave you alone in the summer of 1936. If you go too far, they'll even probably just issue a "warning shot" and a reminder that the Olympics don't last forever.

As an add on, what if you were seen cheering for a Jewish athlete?