Thank you (Frances) for this information. It is very helpful.
Maybe I should provide some background why I immediately believed Nige1 that East was supposed to protect himself in this situation.
For starters, the East player actually
did ask. Presumably he did that because he assumed that he was supposed to protect himself. You say that he didn't need to, but it is pretty clear that East wasn't aware of that. Apparently, it is also not that unlikely that you meet opponents who will play 3
♠ on this auction as a splinter. After all, at least the North player seems to think that it is a good idea.
Now for the background:
I play in The Netherlands and we have a very similar regulation. Here the requirement to protect yourself really means something. If someone forgets to alert a cuebid in the suit where an opponent made a weak jump overcall, then it is fairly obvious that the alert was forgotten. I don't have a real problem that you are expected to ask, rather than let things get out of hand and force some kind of AS on the board, but it is the start of a slippery slope. In The Netherlands we already went a lot further down that slope:
You are supposed to ask when (1NT)-Pass-(2
♦) is not alerted. After all, Jacoby transfers are alertable but extremely popular and they have only been alertable since 2009. You are also supposed to ask about (1NT)-Dbl-(2
♦). In this case, the Jacoby transfer has always been alertable. But the experienced player knows that so many players play it and don't alert, so he is supposed to protect himself. The same goes for (to name a few):
- a bid in the fourth suit (which some play as entirely conventional and others as semi-natural),
- a jump overcall of 3
♣ (which many play as Ghestem, showing both majors, unless they have forgotten

),
- pretty much every double, since conventional doubles have only been alertable for the past year,
- every redouble. Despite the fact that conventional redoubles have always been alertable, everybody thought that they were not since conventional doubles were not alertable. And a redouble is also a double... kind of... isn't it?
- a 2
♦ opening. After all, "everybody" plays Multi.
In other words, if a bid has an alertable meaning which is common, you have to protect yourself. As you may have noticed, a lot of these situations are not about an opponent
forgetting to alert. Most of them occur because players can't be bothered studying 1 A4 of alert rules. They don't
know which of their bids are alertable, they never will and they don't care because the self protecting regulation takes care of things.
I hope you understand my rant against "self protecting" rules. I would like to see a clear stop to "self protecting" requirements. I don't want to be on the slippery slope, even if that means that every now and then there will be an artificially awarded score since someone didn't alert a cuebid where everyone with half a brain would know that it required an alert.
I am usually not a black or white guy but for me the question is "Who do you give the problem: the non alerter or his opponent?".
Rik
I want my opponents to leave my table with a smile on their face and without matchpoints on their score card - in that order.
The most exciting phrase to hear in science, the one that heralds the new discoveries, is not “Eureka!” (I found it!), but “That’s funny…” – Isaac Asimov
The only reason God did not put "Thou shalt mind thine own business" in the Ten Commandments was that He thought that it was too obvious to need stating. - Kenberg