http://411mania.com/wrestling/why-isnt-mark-henry-being-used-on-wwe-tv/

– Mark Henry, age 44, has not been on WWE programming since WrestleMania 32, when he worked the Andre the Giant Battle Royal. Henry is one of the oldest wrestlers on the roster, and has been on record that he will retire this year when his contract expires. According to the Wrestling Observer Newsletter, WWE is keeping him off of TV due to the fact that he is leaving and since that is the case, there is no need to invest any TV time in him right now. This is similar to Wade Barrett, who is under contract through June, but was taken off TV when the League of Nations broke up. This is also likely why they opted to send Ryback home instead of having him continue to work through his deal.

I'd figure they would have him be losing matches on Main Event.

They should let him have a bit of a run before retiring. He has devoted over fifteen years of his life to working for them. Even if it's just a small feud.