Can the data be lost? (Score 1)

That's the first question that you should ask yourself when looking at going outside of the datbase for persistent storage. I would imagine that the data is quite important, and unless you want to write all the necessary functaionality in your one-off data storage solution (which may or may not be slower than the a RDBMS or ODBMS solution) you should have a pretty good argument for why a real database should be used. It sounds like you're working with a pretty uninformed technical staff, to be honest.