No, they would have believed it to be a literal thousand years, just as it is written in scripture. They wouldn't have gone looking for another meaning for "a thousand years." And it's not 6 sets of 1000, but the same thousand years mentioned consistently six times within the context. When you see this, then understand that a thousand years is what God means. It is the same with the number 144,000 that come out of the twelve tribes of Israel. There is nothing in the scripture to lead the reader to interpret that number other than the amount given. The same thing applies to the 200 million demonic army that those four angels gather to kill a third of mankind, or a third of the sun, moon and stars being darkened, or a third of the rivers and fresh water to be contaminated, or a third of the earth and trees being burned up, a third of the creatures in the sea dying and a third of the ships being destroyed, etc.. God is using literal numbers, which those who are wise in their own minds, are not believing. They just go off looking for some other meaning to those numbers, because they read it from the myriad of false teachings, YouTube, seminars, web-sites and hearsay.
Oh I take it that of the apostolic fathers you disagree with them speaking so much about it