I agree the expression "Free Software" has the same problem. However the alternatives also have some problems. He discusses that here: https://www.gnu.org/philosophy/open-source-misses-the-point.... (I'm sure you've already read it, but it's always worth a re-read)

I'm partial to the term "Libre" myself, though in this case it doesn't matter much, since it's a concept that people aren't familiar with anyway and you have to explain it no matter what word you use.