As others have said, they don't expect CHAdeMO adapters to come.
If they supported it, then Tesla's customers would get a rapid charge network by default, as in the UK Nissan is expected to deploy a minimum of 65 CHAdeMO chargers in public locations for all EVs to use. I believe it is the same across Europe.
How would people feel if they provided a way for Model S to charge from CHAdeMO, but no way for cars like LEAF to charge from a Tesla Supercharger?
There could be a perception of iniquity if reciprocity wasn't provided....