The Cat II isolation thing is important.
If you use a soldering iron in a professional environment, everything will be bonded to ground for ESD precautions.
The iron, every other bit of manufacturing and test equipment, work surfaces, workers’ bodies (wrist straps), even the floor, via heel straps (any idea how much conductive floor tiles or carpet costs, and how carefully they must be maintained ? I do)
But once you start bonding things together, you introduce a mode where a failure can, basically electrocute the operators, through their ESD protection stuff.
That’s why good kit is at least Cat II, and the ESD bonding point is not a direct connection to “ground” through the power cord, which should not exist. Rather through a high value resistor, such that any fault condition cannot pass a lethal current to the operator, who is hard-wired to it.
The standards applying to bathrooms, or medical devices, should be the bare minimum.
Weller know their stuff, and I trust them to make professional kit properly.
A copper and steel wound transformer is the perfect isolating device, nothing better. Switch mode PSUs are now very much cheaper, but have so many failure possibilities, even if the designer has any clue about the subtleties.
However stuffing 240V into one wound for 110V is never going to end well.
At least the man recognised that the polyfuse and PTC on the secondary saved the electronics from the over-load. I’d say that was robust engineering.
The man ’effed up, then chose to make a drama out of his mistake. Maybe some additional fuse might have shut it down sooner, but if his workshop was wired up properly it would have tripped that out in milliseconds.
I would not want to work there.