A Pretty Obvious Case

A 10 5 3 2
7
------
A K Q J 10 8 6
------ Q 9
K Q 6 4 3 J 8 5 2
K Q J 10 7 6 3 A 5 4
3 9 5 4 2
K J 8 7 6 4
A 10 9
9 8 2
7 Vul: E-W

EastSouthWestNorth
Pass Pass 1 Dbl
3 3 4 4
Pass Pass 5 5
Dbl All pass

This has to be perhaps the most obvious case of a missed redouble I have come across, and before anyone accuses me of hindsight, lemme point out that almost everyone was in slam. So this pair, and I look particularly to North here, was willing to let a five bid go by doubled, when they're offered a chance for a top board for one trick less? On a redouble?
Well, lemme point out some figures: A bid and made slam brings in 1010. (Everybody was pulling that 13th trick.) Those who got doubled in six spades brought in 1310. A redouble of the five bid -- oh watch how the points add up -- brings in 600 points for trick score, 300 for the game, 400 for two overtricks, and oh yes, 100 for making a redoubled contract, for 1400 points! You don't beat the people in grand slam, but with a five bid, you beat even the people bidding slam, getting doubled and pulling in an overtrick! With that one-trick cushion in case matters go a bit awry!
This pair got 14 matchpoints when they were offered a chance for about an 87% game. Six spades doubled got 82%, grand slam brought 94%, so I split the difference for the only score (had they redoubled) between them. Make no mistake about it: if you're slambound and get doubled at the 5 level, you're being played for a sucker if you let that tamely go by on the fear that there must be something terribly wrong that the opponents know about. That's if you're slambound, now. I'm not advocating redoubling all 5 level contracts, for heavens sake.
But North's quietude is puzzling. His partner has made a free bid of 3 spades where North has five of 'em and about the most powerful side-suit you could ask for, only one possible loser in hearts? It's awfully hard to picture more than the loss of a heart and one spade, looking at the North hand, in which case, you'll come out ahead of the people in slam in you do have two losers and ahead of the four grand slammers if there's one loser. But how do you fear 3 losers in spades, given South's free bid opposite the takeout double, and the North hand?