There's something fishy about this - if you will pardon the expression.
Steamers used in commercial canning operations usually steam-cook the product once it has been packed into the steel containers. The most common variety operate on a continuous-feed gravity-fed track that takes the can through a steam chamber - the can enters at the top with uncooked product and enters at the bottom with cooked product. A large commercial operation would be very unlikely to have a kettle that needed to be filled with cans and then emptied once the cooking was completed. And even if they did have a kettle, how was he not noticed? (I know that the large institutional-sized kettles cannot be started until the lid is closed and the latches secured. It would be very difficult to slip inside one/be slipped inside one as it is being filled without someone noticing - unless a) he were incapable of calling out and b) the people doing the filling wanted him to be in there.)
If it was in fact a track operation, how did he get in the track (should just barely be big enough for the cans to pass by) and presuming he somehow did get in the track and somehow got caught, how coud the operation continue with him blocking the track? If cans are not rolling through I'm pretty sure there is going to be some sort of alarm going off.
It just does not smell right to me.
stay safe.