Guys, I'm putting an end to this thread.
This question has been asked many times on Pokegym and on the Professor forums (I asked it myself there). So far, it has not received an answer. which means that apparently there is a debate about whether or not these get discarded. With as long as it's been sitting without an answer, the question has most likely been referred to PCL in Japan for a final ruling.
Until we receive an official ruling, I would rule that if the card doesn't say to discard, then you don't discard it. It's quite possible that the bit in the rulebook glossary is in error, or is the result of someone jumping to conclusions based on the old TMs (those all got discarded, but they all specifically stated that in the card text as well), or is simply old and obsolete and no one caught it to update it.