All the information about the meaning of "Baptist" is there. It sounds like you are only making an issue out of the ordering of it.... John, that was called the Baptist: for Herod slew him, who was a good man, and commanded the Jews to exercise virtue, both as to righteousness towards one another, and piety towards God, and so to come to baptism; for that the washing would be acceptable to him, if they made use of it, not in order to the putting away of some sins, but for the purification of the body; supposing still that the soul was thoroughly purified beforehand by righteousness.
Compare what Josephus says right before the John passage in Ant. 18.4.5:
... his name was Eleazar, who, for his tallness, was called a giant.
Everything you need to know about Eleazar's epithet is there, except in a different order than the information in the John passage. And I don't see what difference the ordering makes if in both cases all the information you need to understand the epithet is there. Would you be happier if Josephus had written the John passage like that?
"John, who, because he was a good man, and commanded the Jews to exercise virtue, both as to righteousness towards one another, and piety towards God, and so to come to baptism; for that the washing would be acceptable to him, if they made use of it, not in order to the putting away of some sins, but for the purification of the body; supposing still that the soul was thoroughly purified beforehand by righteousness, was called the Baptist."