[RealityVoid]

I mean inert in both the physical sense - they do not move and the chemical sense - sure, metal rusts but the rate is really really slow compared to the liquid dispersion.

Look at the wiki entry linked above by the OP, most things dumped in the ocean are solid waste.

The look at the environmental impact studies done on the dump sites. They found no or negligible environmental impact. If OP wanted to make an argument against ocean dumping of certain nuclear waste, the wiki articles fails at this, on the contrary, careful reading makes it sound like a really good alternative for certain kinds of waste.