So have you actually done any reading on the topic? You are a geologist and using your expertise as an argument that you know what you are talking about, but if you dont use that expertise to read and interpret literature and reports that non-experts have trouble with then you are doing others a disservice and using your qualifications to spread misinformation. DGRs do not need to last "forever" radioactive waste decays to radiation levels equivalent to natural deposits within 10,000 to 100,000 years. As you know, this is a very short period of time on geological time scales and the risk of some unanticipated geological phenomenon cropping up at the selected sites that would operate quickly enough to matter are extremely slim to the point that the risk is essentially 0. Off the top of my head the only two things that could happen that quickly and unexpectedly are impact events and kimberlites. These are two extremely rare and unlikely events that would have far greater consequences than disrupting a DGR.

End of the day, even if we stopped all nuclear power tomorrow, we still need a place to safely store the waste that exists. DGRs are the safest option that I am aware of, but maybe you have encountered other options in your time as a geologist that I have not.