Actually, he's just tired.
(Who wouldn't be tired after dealing with 3 different killer explosives back-to-back?)
theres even reasoning behind this, 9 did the goofy fucking "run across the top bar where the smiley conveniently is" TWICE (if we're counting 10's second phase), shocked(?) twice (18's first and second phase), and exploded (transition from 18 to devil's convergence), i think i would be dead if that happened to me and probably same with the smiley unless plot armor is just that good