Logical Alternatives only apply when discussing a player's action after receiving UI, not misinformation. The Law that's relevant to this case is 21B:
Quote
1. (a) Until the end of the auction period (see Law 17D) and provided that his partner has not
subsequently called, a player may change a call without other rectification for his side
when the Director judges that the decision to make the call could well have been
influenced by misinformation given to the player by an opponent. Failure to alert
promptly where an alert is required by the Regulating Authority is deemed
misinformation.
...
3. When it is too late to change a call and the Director judges that the offending side gained an
advantage from the irregularity he awards an adjusted score.
I think it's pretty clear that the 4
♦ bid was influenced by thinking that West has majors rather than minors. It might not be a great bid (the
♠Q and
♥K are likely to be useless, although West might lead a spade because East bid them), but he obviously wouldn't have bid it with the correct explanation.
So if South bids 4
♦ and the explanation is corrected before North calls, South can change his call (and the fact that he wanted to bid 4
♦ is AI to his partner, UI to the opponents). If the explanation isn't corrected in time for South to change his call, the score should probably be adjusted to whatever happens to 3
♠.
What are logical actions for a club player sitting South here?
What would they be if West's bid had been alerted as "Minors"?
The ruling hinges on whether North-South have been damaged by a mistaken explanation, because East-West's agreement for 2NT is "minors". (Yes - that's a poor agreement but that's what it is.)