Apparently what the pastor meant by Biblical Theology should take priority over Systematic Theology is that Biblical Theology deals with the whole pie, while Systematic Theology only deals with the ingredients, how it is put together, what temperature it is baked at etc.
Thus, according to him since Biblical Theology is the big picture, Systematic Theology flows from our understanding of that big picture (Biblical Theology).
For him Biblical Theology acts as accountability to when he is studying Systematic Theology.
Has he got a correct understanding of the issues? He tells me that when he was in Seminary, he hounded his profs with issues such as this one, so he not naive of the issues.

Tom