Correct. LDraw is made by fans, so while it's less accurate than LDD it's fine to use.
Funnily enough, the LEGO Universe team once provided some official LDD geometry to the fans working on LDraw: http://wiki.ldraw.org/index.php?title=L(EGO)Draw_Parts So by using LDraw, you'd end up occasionally using altered versions of LDD brick geometry. LEGO explicitly gave out those particular bricks though, so it's fine. It's weird how they gave some parts to LDraw but are so concerned about people using any more than that... Who knows what the reasoning was. Probably comes down to different people at LEGO/NetDevil being involved over the years, with different ideas of what to allow.