I’d like to see proof that stuff placed there would actually get subducted (is that a word?) before trying it with nuclear waste.
It’s possible though, that in a few more generations we may wish we hung on to the stuff.
Solid radioactive waste from reactors (3% enriched uranium pellets) become plutonium rich and can be processed into fuel for a second burn. There is no reason, other than Jimmy Carter made it illegal, that we can’t do that.
The resulting solid rad waste is the stuff I think should be recycled via deep-sea trenches into subduction zones.