That looks like a friction fit. Put it in place and try and crimp the tubing just a little bit. This is a ‘controlled pressing force’ type of operation. Don’t hammer or push too hard too fast. Creative thinking can go a long way in training your inner MacGyver (ancient US TV show reference).

One idea is to use a dining room chair. The leg of a chair can exert a lot of pressing force on a small area. This can work if you lack hand tools, a vise or other methods. Position the tube and lower your weight onto the chair in a controlled manner to alter the geometry enough to securely hold the insert in place.

Two part epoxy would be the only type. The catalyst in most epoxies is probably toxic, there are specialty food safe types, but they cost a fortune. I don’t think this is the solution though. I would go with crimping the tube.