The most direct path to 9 tricks is 1♠, 1♥, 2♦ and 5♣. Wouldn't virtually any player lead ♣A at Trick 3, to guard against South having all 3 clubs? (If South shows out on the first round of clubs, you still have a chance to switch to spades and collect 4♠, 1♥, 2♦ and 2♣.)
It cannot be, at IMPs, that the expected value of GIB's chosen line of play is higher. I had stopped posting declarer play issues, but this continues a recent string of "just take your tricks and make your contract" posts.