I doubt that be remotely true. I would like to see some facts backing this up because EA and every other publishers spent seem to had any problem selling dlc on steam prior to crysis 2 being pulled.
Before crysis 2 publishers and indie developers praised valve on their transparency, ease of content delivery, and low asking prices. Until Valve releases a statement we have no idea what happened to cause the rift unless your willing to buy EA's PR statements as fact.
Unless you're going to claim EA is blatantly lying it is all we have to go on. The FACT that Crysis 2 was pulled after DLC was released and the FACT that DA2 was pulled right after the newest DLC was released paints a pretty clear picture though. From the sounds of it the policy change happened not long before Crysis 2 was pulled, which explains why no one else had problems prior to that and explains why other titles that use a similar system and have stopped getting new content (say Mass Effect 2) haven't been pulled.