This appearance seems pretty consistent with the rumors that Taker had been on the fence about whether he would or can go for a match this year. It's not like he suddenly showed up on Monday RAW TV. Seems consistent with the idea of him wanting to see if he can work a match. He obviously gained more weight and if he did have shoulder and hip surgery since Sept., no surprise if he put on some pounds and isn't as jacked as he used to be.
Rasslin' is pretty superficial, so looks count. But he also has a gimmick that doesn't require someone to be ripped or to look young. He doesn't have to look idea, in fact it probably takes something away if he looks too nice. What matters most if he were considering a match this year is whether he can physically perform. Having a few extra pounds is not something that defines that for what he does. There are plenty of legitimate, fat athletes that can make guys with Cody Rhodes physiques look like out of shape, weak-ass slobs.
Cena showing up fat would be one thing. Guys like Kane or Taker can gain weight. They're monsters, they don't need to look pretty.