Tell him to open up the keyboard and figure out how it was constructed... If he has the money to buy a new keyboard, I am pretty sure he won't mind breaking this old one into pieces.
I believe you are talking about the stem. If it is a QFR, it is plate-mounted and you will need to do some soldering work to fix it in the "proper" way.
Otherwise, carefully apply some adhesive on the broken stem, you don't want to get it into the switch. I won't recommend this to someone who can break the stems. Maybe you should offer to do it for him.
^ This...
Personally, I'm not an idiot so I should have offered to swap his keys for him by the sound of it!! I suggested some strong adhesive (Something like Araldite) applied to the stem (Thanks for that terminology) but I don't think he will go for that even though he was all "Yeah that's a good idea, I'll try that".
I think it will probably end up in as you say, breaking what he has and ordering a new one anyway but I suppose it will give me a good laugh watching him attempt to fix it (I will see if I can get some pics for you to enjoy also). I guess both him and I learned something valuable today...
He learned - Being more delicate can take longer to do something but won't cost you all the replacement fees on something you love...
I learned - Don't expect an idiot to achieve something that requires patience and a thoughtful approach.
Dan