Are you the only owner/operator of the grill?
There's some smoke on the bottom of the kettle. That normally only happens momentarily when theres a big hot, greasy, fire in the grill that was allowed to burn unchecked, then the lid gets put on (to control it) and the heat & flames jump out the bottom vents briefly.
All that heat didnt appear to melt the table top, or it was relpaced after.
Im not familiar with the gas supply line being metal, Iv only seen rubber lines on older SS grills.
My first guess is the touch & go was used with a big pile of fuel and was left unattended while the rig went nuclear and had a melt down.
Second guess is there was a gas leak from a broken part that torched some stuff.