Now seemed the right time to use it. Nothing else was working and the main stars were taking a nap. They needed a play for time to reveve those two and the only capable of creating that diversion effectively is 8th Inner Gate Gai.
I think the timing was actually okay here. Besides, all the damage Gai is inflicting on Madara is just going to be healed by Hashi's Sage Mode.
This...
Madara will heal and get back to normal.
Also, he's just having fun and not using his full arsenal, which we'll get to see when Naruto & Sasuke come.
I respectfully disagree with the statement in bold. I think Maddy is actually trying, but Gai is just too fast at the moment. Maddy is tough and can take the damage though, this is why he is enjoying the fight. Because it actually is challenging to him. But Maddy will catch on to Gai's movements sooner or later and thanks to his Sharingan he will be able to aniticpate the movement. Then I think he will start tagging him with Rinnegan techs and such. either that or he is just holding out until he can find an opportunity to get his other eye back. Whichever. I
Again, I think Maddy is trying, but I also belive he is holding back the lion's share of his power simply out of pride.