This whole 'Open Source' thing is a bigger pet peeve than it should be, because I've received criticism for using the term on a page where I literally just posted a .zip file full of source code. The smart thing to do would have been to ignore and forget the criticism, which I will now work harder at doing.

In the case of a pork producer who labels their products as 'vegan', that's different because there is some authority behind the usage of 'vegan'. It's a standard English-language word that according to Merriam-Webster goes back to 1944. So that would amount to an open-and-shut case of false advertising, which I don't think applies here at all.