Following hand and auction, screens are in use.
4NT is alerted and explained as "unusual NT, both minors, min. 55" to South. No further alerts or questions. South chooses ♥, which results in 6♣+1. ♠A lead would result in 6♣-1.
It turns out that 4NT was not "unusual NT" but simple asking for aces. It was explained to North as such but this information does not reach South. TD is called and the following argument is made:
1. 5♦ was interpreted by South as preference for ♦, obligatory response, i.e. could be with zero values.
2. 6♣ shows a much better ♣ than ♦. At least 65 and solid ♣.
3. East bidding 6♣ shows a very strong hand and quite likely no ♠ as East bid this alone without West showing any value (other than some ♦).
4. Among the 6♣ that can be defeated, he envisions a 6520 with Kx in ♥.
5. He is afraid that a ♠ lead is ruffed, trumps are drawn and he can not ruff the ♥, i.e. 6♣=.
6. Thus, he hopes for ♥A by partner and a ♥ back for 6♣-1.
7. Given the correct information (asking for aces) he clearly knows that East has 2+ aces.
8. He does not assume 5♦ and 6+♣ but 7+♣.
9. He would not assume the ♥A by partner as he knows where all 4 aces are (the response to 4NT, asking for aces is also 5♦, showing 1).
10. Thus, he would lead ♠ for 6♣-1.
Remarks:
1. West did not correct the 6♣ to 6♦. He holds J2.QJ95.AQ876.84. I would argue that after 6♣, he must correct to 6♦ or realize that the 4NT is not unusual NT showing both minors. In the later case he should have told this to South. He did not.
2. All other tables playing in ♣ (four or five) found the ♠ lead.
3. No CC available.
What to rule?
1. I would rule MI. The 2007 laws explicitly state that lacking evidence to the contrary, you must favor the NOS. Not correcting tha 6♣ to 6♦ makes the case even stronger. West likely knew. Law 21B1(b).
2. The NOS was damaged. Without the infraction (MI), the result is 6♣-1, which is more favorable to the NOS than the actual table result of 6♣+1. Thus, damage exists and the TD must redress it. 12B1.
The only remaining issue is 12C1(b), SEoWG:
1. One might argue that the ♥ lead is a serious error (I do not think so). This is still not enough as it is not "unrelated to the infraction". Instead, it is a direct consequence.
2. This leaves the wild gambling. Did he deliberately to do something extraordinarily off-beat? I do not think so. One has to choose between ♠ and ♥. Both have some merit. One can argue that ♠ is the better choice, but does this reach the WG level? Is it really insane?
3. One can not really use the double barrel argument, either. The auction looks perfectly normal to South. East has a significantly better ♣ and West has a marginally better ♦. Plausible. Thus, he can not assume that there was an infraction and play the less likely option. In fact, even than and there he clearly claimed 6+♣, exactly 5♦, no ♠.
What would you rule? I am strongly in favor of the ♠A lead, which gives 6♣-1, no matter what, due to the particular split of cards and the lack of decisions to be made.