I am sorry, I am a bit confused. What KLM is saying are not facts or what you are saying are not facts, (just what you remember).
KLM has been jerking me around for a while now. I do know that most of their aircraft don't provide in seat power in economy class.
Are you sure that they provides 110/220V ac in buisness class?

Since KLM did not allow me from using my CPAP I never tried to connect my CPAP. I don't know what kind of power they had in the business class on the three flights I took on 747s.

I would appreciate of someone can confirm.

They probably have 110/220 in the lavatory too. I think it would be easier to provide 110/220V ac than 12 volts dc, if they are going to make special provision to provide power in economy.