An engineering professor may very well be a fanatical Nazist who would gladly fail any students he discovered harbouring pro-democracy views, but he's not going to discover them

That reminds me of the biology teacher who, when asked to write letters of recommendation, demanded that his students swear allegiance to evolution. A student sued in 2003. Some time between February and April, he added a little disclaimer. That form remains today. Of course, this was only for letters, not grades, and it was all put forward in writing ahead of time.