Holy crap, we have a ****ing weeaboo on our hands. I speak on behalf of the general user population of narutobase when I say that Sir Derp Obito is totally missing the point of the Naruto series, and making himself seem like a deranged-Naruto-otaku with all these ridiculous threads about japanese language, history, and culture.
ETA: *L-o-l* @ the sheer number of posts saying thank you that Sir derp obito has filled this thread with. Like anyone actually appreciates you wasting your time posting irrelevant threads like this.
That doesn't prove he is a weaboo... He is very insightful and he finds common links between the manga and common Japanese mythology and then logically deduces where Kishimoto got inspiration from. If anything, you pointing out that he is a "deranged Naruto-Otaku" has less merit because liking only one anime, especially one of the mainstream three, is not a pre-requisite for one to be considered an Otaku.
Yes, it's very possible that Uzumaki clan is inspired from Urabe Clan, but your theory "Rikudou Sennin is Uzumaki" is based on that mask...Because mask connects us with bodhisattva.
However, I found something interesting in your theory...Well, much more interesting than "Rikudou Sennin is Uzumaki".
When I was analysing your theories I found connection between six realms (rokudou) and Rikudou. Mainly because of the same title that these two words have (kanji) 六道. But I realized that these words are different: six realms (ろくどう), and Rikudou (りくどう). However, Rikudou can be translated (??? ...only if we are searching meaning of his name, because his name/surname is RIKUDOU!) as six paths (in the meaning realms) to some degree, although there are some problems with that. NOTE! See the kanji details!
Only those who attain enlightenment, the Bosatsu (Mahayana), the Rakans (Theravada), and the Nyorai (Tathagata or Buddha, in both traditions) are free from the cycle of birth and death, the cycle of suffering, the cycle of samsara (six realms). You know what is the place of Bodhisattva here, I don't have to explain that.
So if you're right, what I'm going to tell as conclusion is actually spoiler.
I'm not sure he put much thought into the 'type' of mask he drew to be honest. If he was to make a reference to masks and the demons they represent the more fitting mask would have been a Tengu mask, for sure. I think the style of mask shown was chosen because the Death reaper seal has the same appearance and the mask picked up in the scene u showed was to be connected to those seals. I think it's more of an anime story line thing than a reference to real life.