Kaguya didn't use Gentle Fist. She blocked the chakra points of the hawk. Madara blocked Hashirama's chakra points using his black rods leaving Hashirama unable to mold chakra. She shot hair at them, Gentle Fist works by injecting chakra.
And in the likely even that she did in fact use Gentle Fist, it's Kaguya. Her chakra and the power behind her techniques far surpasses anything any Gentle Fist user in the Manga can accomplish. Gentle Fist doesn't do anything worth mentioning to ANY level of Susanoo from Ribcage to Perfect. In an actual application of the jutsu, something you fanboys love to ignore, the Gentle Fist user would take a very unrealistic amount of time to destroy an entire Susanoo even if it were Air Palm as they'd have to channel enough chakra through the construct to destroy it. He was able to easily destroy Kido's webs because he doesn't need to release that much power.
In an actual battle, another thing you fanboys love to ignore, any level of Susanoo on it's own combined with the user's abilities results in any Hyuga shown in this Manga being slaughtered with negative difficulty. A Kunai can kill Hashirama yet anyone using a Kunai to fight against Hashirama gets raped. Same logic here. So no, Gentle Fist is in no way, shape or form a good match for Susanoo or any chakra Avatar/shroud shown in this Manga. Not at the level that Neji, Hiashi, Hinata and Hanabi are at.
It'd be nice if you could refute this so we could have a somewhat decent argument, but you won't because that's not how fanboys and/or trolls like you operate. I also find it ironic how the people supporting Byakugan are the first to call someone butthurt yet they feel threatened enough by a fictional power in a fictional Manga that they make the same threads over and over, day in and day out, pleading their case about how their favorite Dojutsu is the best Dojutsu.
:lol Grow up children.