Yep, the handles are metal, so using the metals handles to pick up an extremely hot jar could crack or shatter the glass. If it's the final bath, the jars are filled with food and it's boiling hot. What if one of the kids was standing next to this dumb bell and the jar broke with the scalding contents?
It shows that she knows nothing and the Netflix people don't either or someone may have told her she was using the tongs wrong and she blew the person off or yelled at them.