You would probably have to call and ask, but Free QSDP doesn't seem like it would be a good deal at a Moderate.
Regular Dining Plan was just too good of a deal at the Values.
I suppose if you don't qualify for any other package discounts, then it might be ok.
I have an AP, so the only way I'll book Free Dining is at a Value, because the AP discount is better at the Mods and Deluxes.
I guess they don't let the general public add the Dining Plan with their Room-Only discounts though.