It still wasn't stated that you needed to solidify to attack when you have both the eyes.Kaguya wasn't aware Kakashi phased through her attack. And Naruto isn't in the same league as he was when he first faced Kamui. He's undoubtedly the fastest shinobi alive right now. No contest. Kakashi ain't a threat. Even if he did hit Naruto, he'd just heal from it whilst countering Kakashi, who has to be solid when he attacks.
Also, Kaguya can't react to Kakashi obviously phasing straight through her attack and activating a bright Raikiri, but she can react to Sasuke's instant teleportation? So, by that logic, Kakashi speed blitzes instant. He's even faster than instant using your logic.