Not to stir the pot, necessarily, but...
Volnutt, I think you might still be reading the Didache as a Protestant would. Many Protestants, and there's even been a bit of a re-surgence of this recently I think, are obsessed with following the practices of the "early church." They want to do what the "early church" did, and believe as the "early church" believed. And so, in fitting with that, you have pulled out the Didache, a document of the early church.
However, in doing this, you read back credobaptism into the text, and reject (or at least question) later Orthodox teachings mentioned here. You're taken the Didache, kind of added it to Scripture in a way, but you still read it through Protestant eyes of the "early church." I don't think I mispeak (someone correct me if I'm wrong) when I say that the early church for the Orthodox is just that...the church, but earlier. The Orthodox Church is that same Church, and is embued with the same doctrine and same authority as it was, because they are the same Body.
And so, when we read the Didache, we read it in context with the whole Church and all of the Holy Tradition we have received, as St. Paul says, by both spoken word and epistle (2 Thes. 2:15). The Church, as a whole, as always taught us baptism for the remission sins, of both infants and older converts.
And so, like has been said before, you would have to present a solid line of teaching in the Church that supports credobaptism. And, you can find credobaptists in the earlier centuries of Church history. I can't think of a single one that was not a heretic, and their dogma on baptism was part and parcel of that heresy.
In short, The bottom line for Orthodox is not derived from over-analyzing and pulling out a single document, set of documents, etc. but examining the entire scope of Holy Tradition that has been taught and handed down into the present day. That Tradition, which we see as from the beginning, from the Apostles and Christ Himself, is the baptism of both infants and converts, for the remission of sin.