The “spout” is a drain valve but on looking at the image I can’t see any way of isolating it.
Most moder radiators will feature something similar to the below image. As you can see, just after the drain spout on the left, there is a valve lockinging screw that can be screwed in to lock the valve off.
I would suggest, unless he can find a screw or nut or anything similar which will allow teh valve to be closed off, you will need to change it to a similar lockshield valve as seen in the image.
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