Hey Whisker,
I am no expert on the Traditions. But your question piqued my curiosity, and I just spent some time rereading the Traditions from our Basic Text. I didn't find an answer for you that I can cite from the Text. But as I was reading, I realized how strongly I felt about your situation, and I wanted to let you know my understanding of the issue:
We hold NA meetings to carry the NA message of recovery. An AA member leading an NA meeting may confuse the newcomer.
If your group is lacking a suitable lead, maybe you could have a literature meeting that night. Or open by asking if anyone has a recovery-related topic to open the discussion?
Best of luck to you and your group. Thanks for giving me a good reason to revisit the Text tonight. I really needed that.