Does DVD support non-interlaced formats (576p)?
I had this issue come up a few months ago, and what I found out was that the video stream frames, irrespective of source properties (field or full frames), are stored as field pairs in authored VOBs, although the scan mode and order is correctly noted in the metadata for benefit of players.

I've had multiple DVDs of progressive source accepted by Amazon Createspace. So you can go ahead and deinterlace.