Yea he's 100% TDD in the UFC but neither Faber nor Muhnoz has great TD's as far as numbers goes, fairly sure their accuracy is low and Faber got his leg fucked up halfway through the fight.
I think the best evidence is that Rivera looks good defending TD's in general, probably wouldn't go undefeated during 19 fights since 2009 against mostly fairly high level opponents without some solid TDD and seems very athletic and well built to defend takedowns.
I really think we need to consider the 19 fight winstreak against four UFC opponents, a bunch of opponents that later ended up being in the UFC and a bunch more of high level regional talent. He's not a can crusher, he's well rounded and he has won mostly decisions. This is the kind of guy who just doesn't fuck up very much.