I agree with the assessment but, by what research I understand, it should work. My manual states that the display supports a VESA 640x480, 31.469 kHz Hor Freq, 59.940 Hz Vert, 25.175 MHz Pixel Clock, -/- Sync Polarity. This is one of many supported modes, but I think the Dreamcast outputs here.
That might give an idea of what I'm using. It should output at "640x480p60 (Progressive Scan, EDTV standard) at 31 kHz in RGBHV".
Does anything there give you any indication it wouldn't be supported?