I wanted to say exactly this (the first part, I don't care enough about Stallman to have any kind of opinion about him). In plenty of countries in the world (including UK) the age of consent in 16 (which personally I find problematic but there's nothing I can do about it). So the objection Stallman raised is not irrational. Not only was it not "forcing someone to have sex against their will" but if it happened in a different country it would have been completely legal. Of course it did not happen in another country, it happened in a country where it was illegal, so it should be investigated and prosecuted but as sleeping with an underage person not as rape.