There are other problems as well. It will not compact properly and will settle over time as the organic material degrades. Organic material also tends to impede drainage.

No. When the grass decays, it leaves holes in the dirt, which in turn may be come sub-surface erosion channels. Then one day the whole shebang collapses a few feet, with you and the lawnmower in the resulting sinkhole. Or the erosion channels undermine the retaining walls and the walls collapse.

Pile the weedy sod somewhere, root side up, and cover it with a pile of something compostable. In a couple of years, use it somewhere.

Thank you for your valuable feedback!