I don't think aggression has much to do with the factual content of the replies. Just because people reply to you angrily about an issue that is near and dear to them doesn't mean you can talk about them dismissively like this.
The aide said that guys like me were 'in what we call the reality-based community,' which he defined as people who 'believe that solutions emerge from your judicious study of discernible reality.' [...] 'That's not the way the world really works anymore,' he continued. 'We're an empire now, and when we act, we create our own reality. And while you're studying that reality—judiciously, as you will—we'll act again, creating other new realities, which you can study too, and that's how things will sort out. We're history's actors...and you, all of you, will be left to just study what we do'.
It's actually a poignant, forward-thinking point about the malleability of "reality" and "facts" under empire, but predictably the third-way neolibs that still dominate the party failed to grasp that and first made a joke out of it, and then out of themselves as it was realized.
The other commenter is correct that Colbert coined the term. It's true that there was a lot of talk in that era about who did or didn't adhere to "reality" and how that related to partisanship, and a segment of the blogosphere that described themselves as the "reality based community," in reponse to that Rove quote, but none of that background context has anything to do with anything when it comes to the fact that the phrase itself, "reality has a liberal bias" is something that came from Colbert.
Of course it was in an intellectual climate where those words were charged with political meaning that made them salient enough to set up the joke. But to say it didn't original with Colbert would be to say that phrase itself was coined by a different person, and if it was, you could say who it was, and when and where. Otherwise it's just a confused detour into the weeds that lost track of the original question of attribution.
This is a huge detour, so to tie it back to the original thread, I think talks of "bias" are poisoned by a false assumption sides are equally estranged from scientific truth. It feels fair to make a both-sides argument, but it really just doesn't hold water under any serious examination especially when it comes to which party affiliation more systematically aligns with, responds to, and believes in scientific consensus.
Being extremely concerned over the precise origin of one particular phrasing of the joke rather than its context and influences is hilariously on-point for the 'reality-based community.' Judicious!
But you see how harmful it is to the site to do explicit political flamewar. Yours was the only non-aggressive reply out of five.