No. Starting in HD, and making a DVD will look a lot better than starting in SD and doing the same. Starting out with better quality always will. Just like shooting film, or 2K or 4K will look better when made a BluRay than shooting just 1080...or 720p.
Plus, you are protected for HD. If some day you want to burn a BluRay, or give someone an HD QT file, or post on the web, you are set....already in HD.
Just a compressor setting:
#42 - Quick and dirty way to author a DVD
Shane's Stock Answer #42 - David Roth Weiss' Secret Quick and Dirty Way to Author a DVD:
The absolute simplest way to make a DVD using FCP and DVDSP is as follows:
1. Export a QT movie, either a reference file or self contained using current settings.
2. Open DVDSP, select the "graphical" tab and you will see two little monitors, one blue, one green.
3. Select the left blue one and hit delete.
4. Now, select the green one, right click on it and select the top option "first play".
5. Now drag your QT from the browser and drop it on top of the green monitor.
6. Now, for a DVD from an HD source, look to the right side and select the "general tab" in the track editor, and see the Display Mode, and select "16:9 pan-scan."
7. Hit the little black and yellow burn icon at the top of the page and put a a DVD in when prompted. DVDSP will encode and burn your new DVD.
NOW...if you want a GOOD LOOKING DVD, instead of taking your REF movie into DVD SP, instead take it into Compressor and choose the BEST QUALITY ENCODE (2 pass VBR) that matches your show timing. Then take THAT result into DVD SP and follow the rest of the steps. Except you can choose "16:9 LETTERBOX" instead of PAN & SCAN if you want to see the entire image.