It's confusing to me too when it's phrased that way. Stallman's original quote makes much more sense, "Think free as in free speech, not free beer." In other words, contrasting free as in "no restrictions", versus free as in "no cost".
Even as a non-latin speaking person I can identify the difference between those types of "free".
Or, alternatively "Free as in Freedom", which is another phrase I've heard coming from the FSF.