Maybe madara was allowed because he also has the god tree inside
Obito says he can't travel between dimensions, that doesn't say anything about if Madara can or can't. I'm thinking Madara has the juubi under better control, like on a tighter leash, so he tells the juubi where to go. It's either that, or you're right and it's plot.
we can just assume U_UThe Left eye is perhaps special ?
Go read the viz translation ffs...
Madara is an OG
Kishi just had to nerf Juubi Obito it's obvious... Also the Madara trolling is getting out of controll first he tamed Juubi like it was nothing then he takes Kakashi eye and use Kamui with a span of 2secs c'mon Kishi...
Im sure Madara is familiar with Kamui. He may even have been able to use it with his EMS.