I really wouldn't call it conclusive proof. But also, we havn't seen Madara/Tobi use an MS have we? When he was going all over the place with his teleporting, we didn't see his eye.
But also, if Kakashi had more control over his MS (ie. if he was Uchiha) then maybe he would be able to teleport individual parts to other dimensions and not cause them harm. Or what if it depends on the user that ACQUIRES the MS. When he got Obito's eye, kakashi didn't have MS, he acquired it later so later on Obito may have acquired it in a different way if he were Tobi.
Now, I don't necessarily agree that Obito is Tobi/Madara but this isn't really conclusive proof.
But also, if Kakashi had more control over his MS (ie. if he was Uchiha) then maybe he would be able to teleport individual parts to other dimensions and not cause them harm. Or what if it depends on the user that ACQUIRES the MS. When he got Obito's eye, kakashi didn't have MS, he acquired it later so later on Obito may have acquired it in a different way if he were Tobi.
Now, I don't necessarily agree that Obito is Tobi/Madara but this isn't really conclusive proof.