It's no more a "semantic quibble" than any other inaccurate use of a term is a semantic quibble. People are counting on headlines meaning what they say they me

It's no more a "semantic quibble" than any other inaccurate use of a term is a semantic quibble. People are counting on headlines meaning what they say they mean, and this one doesn't. If the headline mistakenly said "Lisp-compatible" instead of "Python-compatible", you wouldn't say "Oh, that's just a semantic quibble", right? You'd say it's wrong, flat out. The programming language it's compatible with is Python, not Lisp, so saying Lisp would just be inaccurate. (And they're both English words -- neither term is trademarked, obviously, and they both have meanings unrelated to their meanings in the realm of programming languages.) Saying this is "open source" is wrong in exactly the same sense. The term has a settled meaning in the software world. The reason "non-commercial usage is incompatible with all the major open-source licenses", as you say, is that it is by definition incompatible with all open source licenses. Because "open source" means freedom for use for any purpose, including commercial purposes. This is not merely a semantic quibble any more than any other wrong use of a word is a semantic quibble. It's wrong in the normal way that language usage can be wrong.