Apparently the claim that the word "president" used of the officiating "minister" is ancient is based upon the appearance of the word in the First Apology of Justin Martyr (circa 155) in chapters 65 to 67. Certainly we find there that in the descriptions provided by Justin of the Rite of Baptism and of the EUCHARISTIA we do find that that the officiating minister is described on several occasions as offering prayer - "When the president has given thanks" -- and as preaching -- "the president verbally instructs and exhorts...."
However (and this is a big however) what we find if we read the Apology from the beginning of chapter 65 is that at the first use of the word "president" this word is part of a phrase which can be translated either as "the president of the brethren" or "that one of the brethren who was presiding. The sentence reads: "There is then brought to the president of the brethren bread and a cup of wine mixed with water" or "There is then brought to that one of the brethren who was presiding bread and cup of wine mixed with water."
So the use of the word "president" in chapter 65-67 is in fact shorthand for the longer expression and obviously refers to the chief pastor, the one who usually chaired the board of presbyters and the meeting of the whole Christian congregation, -- the one we call the bishop. A similar description of the bishop (but it can also refer to a presbyter when a bishop is not present) is found in the Ecclesiastical History of Eusebius IV, chap 23.
Further, the assembled faithful baptized Christians of both sexes are called "the brethren." (Justin describes how the new baptized are brought "to the place where those who are called brethren are assembled in order that we may offer hearty prayers...")
Thus I recommend that where the word president is used of the bishop or the presbyter that we insert the missing words so that the full description be used, "the president of the brethren."
P.S. As a follow up on my earlier piece on the ordaining of women and the different background reasons for it, I strongly recommend to those who really want to know the reasons for it in North America to study ORDAINING WOMEN. CULTURE AND CONFLICT IN RELIGIOUS ORGANIZATIONS (HARVARD UNIV PRESS, 1997) BY PROFESSOR MARK CHAVES.