Cleaning up the terminology: as everyone is saying, technically 1S was the overcall, and 2H was a response (in competition). I would also agree with all that (in 2017) this wasn't, and isn't after the 2021 changes, Alertable in the ACBL. Note that Alerting regulations are country-specific, but I can't believe that there is anywhere in the world that would require an Alert for 1C-(1S)-2H promising 5.
My guess is that partner is in a world where not everyone plays negative doubles, and many people would respond over the overcall with 4, so she thought she was being helpful. Unfortunately, that is not the "normal duplicate world", and instead it caused a problem, which I'm not seeing much discussion of.
While I don't like the reaction of the Director* (who should be especially careful when playing and "ruling" at his table), he's got a point, and I want to explain it.
Bridge Communication is meant to be done between partners solely by means of the calls and plays (L72A1), and to opponents as the Regulating Authority requires (L40). Alerting this call is so unexpected that it will almost certainly prompt an ask (if the "alert" was a straight up explanation without being asked, which I have seen, that's worse), so opener gets to tell partner what she thought partner's bid meant.
Keeping partners on the same page via the Alert procedure - especially with a "not Alertable" call - is not legal. Even if that was not the intent, it does "just make life easier", which is a problem. So this needs to be stopped before it becomes a habit that gets relied on. Thus the director's comment.
You don't have to understand the Alert Procedure completely (I don't understand it completely, and I have to rule if something's Alertable!); you do, however, have to know what parts of the system you're playing are Alertable, and do it correctly. I hope that was the intent of the TD's correction.
* Although as a TD myself, I know several bridge players who react to any correction, delivered as gently as possible, as if I had "gone into a flat spin". So I'll do my usual (which is usually close to correct) and assume it was an "you don't Alert that!" - more blunt than it should have been, less fly off the handle than it sounded to the newer, possibly intimidated by playing against the director, players.