I for one don’t see the issue with that “to be fair” statement here. The parent used it merely to announce that they were going to take the counter-point to the most likely community view, i.e., they were going to defend Reddit’s action of not naming Swartz as co-founder. They then proceeded to do so by explaining that Swartz never really played a co-founder role. The comment implied “to be fair [to whoever at Reddit made that decision] and then went on to provide supporting argumentation.
It’s quite different from the lazy use of the phrase, e.g., “to be fair, both sides suck” that you may find in political discussions without supporting arguments, for example.