This is from Ray Henson, who isn't exactly known for sensationalism:

Wow playing WSOP live action, some guy walks up to a seat that a player is away from and says "my friend wants me to cash him out" & makes off with like 50k! Obv by the time the guy comes back to table the culprit was long gone! They are taking reports from everyone now but says he is responsible for his own money.
For those of you askin about the "robbery" at Rio last night, no th players in the game didn't stop him! Unbelievable! I wasn't at the table but I was a few tables over. Obv the story has prolly been exaggerated, but that's what I heard right away. I'm sure that the WSOP live action floor staff will be able to find out who it was and I'm sure he will be caught, but he did get away last night!
If the Rio really let this happen and doesn't make good on it, that is really terrible.

This is especially true because, unlike games such as blackjack, you aren't allowed to take your money/chips off the table when you temporarily step away from the game, so you need to have faith in the security model of the room to take care of your money.

We will be discussing this on radio, and maybe will try to call the Rio cash section (if they can be reached by phone) and see if we can talk to them about it.