I promise you that this display has some sort of scaler (upconversion) technology. LCD, Plasma, DLP, HD-ILA etc. are called fixed pixel displays. This means that they do not raster (scan scan electrons) at different frequencies.
If you are to fill the entire screen, the display must scale (upconvert) the content to match the panels resolution. If they didn't, when you feed the display with a 720x480 DVD image, i would only fill the center of the display and you would have black bars above/below and left/right of the image.
Now it is possible that the Toshiba doesn't have a scaling story or it may do a poor job of scaling (I cannot judge as I have never viewed the display) but it does some sort of upconversion.... It has to.