That was the dumbest thing i've heard today.
She can't even keep up with Lee's speed and her taijutsu pales in comparison to Lee's. Lee in the first gate is enough to take her down, if she some how manages to live through that secondary lotus will take care of her. Even if Katsuyu does heal her she won't be moving and most likely will be unconscious.
Gai could easily take out Katsuyu with Asa Kujaku; you take out the main body and the others go with it. Tsunade won't be hitting Gai in the 6th or 7th gate. She can attempt to use byakugou but, it doesn't last for ever. Her taijutsu isn't even close to the level of Gai's and neither is her speed. She may have broke a V2 Susano'o rib cage but, one Hirudora from Gai sent it flying into a mountain. He wasn't even in EIG when he did that and he was also being crushed by Mokuryū.