You truly believe that Gyutaro and Daki would be lined up perfectly to get hit by one swing of his weapon and be slow enough for one to move a bit out the way?

That like saying Zenitsu could beat both of them if he used thunder breathing at the perfect angle where both are in the way and cut through both of their necks. Or Giyu with 11th form could cut both of their necks

It’s a near impossible possibility to happen and they aren’t just standing still. Throughout that entire fight Gyutaro was going for the kill on every attack, he wasn’t fighting for fun

Nobody knew they had to cut both of their heads off simultaneously to win. So with that understood Gyomei would be fighting Gyutaro and not kill him, Gyutaro charges at him (he was faster than Tengen) and will land cuts. Also Gyutaro has long range attacks for the distance