Quote
Clearly West should not have said "support" with such confidence.
Why not? Surely it is possible to be both confident and wrong.
Quote
An offer to lead the table was appropriate.
What does this mean?
Quote
I was under time pressure (entering scores from datum sheets) with nobody to refer to. Small likelihood of an appeal.
That's why we get paid the big bucks.

The likelihood of an appeal should have no bearing whatsoever on the ruling.
Throwing the board out is illegal, as others have noted.
There are two problems here: NS have MI from West's erroneous explanation of the double (it appears the correct explanation is "we haven't discussed it"

)
and the explanation is UI to East.
4
♦ is a bad bid, but it doesn't reach either wild or gambling. IOW, it's an error, but it would need to be judged a serious one to invoke Law 12C1{b}.
Would North or South have done anything different with a correct explanation? It doesn't sound like it — so I'd say no damage from MI*.
Did East, who had UI fail to carefully avoid taking advantage of it? It doesn't seem so — which would lead to a conclusion of no damage from use of UI.
On that basis, I'd have ruled "result stands".
* If accepting North's argument that it was the MI that led him to bid 4
♦ (which is reasonable to do), then there
was damage from MI, and NS are due a score adjustment. How would that work? Well, I am kinda split between 4
♥-2 and 3
♥-1, so I'd weight it 40% of the former and 60% of the latter (Australia being a 12C1{c} jurisdiction). Given the MI, I don't think 4
♦ can be judged "serious" if N says that with the correct info he would not have bid it. So no change due to that. What about EW? Well, if you give a weighted score, you shouldn't split it. I would give NS +140, EW -140.
East would have to convince me he might bid 3NT over 3
♥. If he did, I'd include some portion of that in the weighting.
Throwing the board out is TD error. I'm going to assume the correction period has passed, since I don't want to try to figure out how to fix it, but if still in the period, Law 82C applies.