It’s been a bit, but if I recall, it’s that the dishwasher already reliably cleans unsanitary things that are loads more biologically risky like cutting boards used for raw meat or potentially contaminated with things like Norovirus.

I could see it being safe from a germ perspective but when a little nugget of shit rattles around in the machine and ends up anywhere near what you're using to eat that's gotta suck, safe or not.