I see all sides of this.
I wouldn’t go to the Sun but I’d be really unimpressed if my child burned themselves and didn’t get medical care. Clearly the hospital didn’t think it was nothing since they advised him to go back for a check up three days later.
From a teacher perspective, accidents happen and sometimes children don’t tell you they’ve hurt themselves (often because they think they or someone else will get in trouble for doing something you asked them not to!)
I have taught for a decade and never thought to use hot glue guns with my class, so I’m not too worried about those being curtailed. I doubt they are in much use in a primary school!
A fulsome apology and promise to review the risk assessment should be the consequence if it’s a one off thing. No one should be losing their job.