Seeing how much of a train wreck EA is, I wonder if some of it is the fact that it's not worth $6m to deal with those clowns.
Ogre's super cynical take:
Six months ago it looked like EA and some of the other CCS charging networks are getting their stuff together and so the Tesla Supercharger advantage was going away. By opening things up they could scoop up those customers from the nascent competitors. Now, after seeing how terrible the EA expansion went, with bricked trucks, frozen chargers, and exceedingly bad reliability.... maybe Tesla figures they can just retain their competitive advantage for their vehicles for a bit longer.
Slightly less cynical, maybe Tesla figures this is the opportunity to push harder on the NACS effort to get some other companies onboard. I could genuinely see Ford throwing in the towel here and switching to NACS. If they did, I think the rest of the industry would eventually as well.