All of the code that steemit produces is 100% open source. There is a little bit of debate around whether or not this particular open source license qualifies as "free software". I think it does, because it is relatively permissive. Some disagree. It's a minor point, because the only restriction on it is that it must be used on this blockchain.
Dan was the one who chose the license in use by steemd. In his resignation post thread he explained why he left, and it wasn't the license.