This has nothing to do with the nature of the scientific proof, or the quality, magnitude or the number of replications. None of those criteria apply.
I am an outsider to this field who, like most people, would prefer that future human generations not be decimated.
I also have a great deal of respect for academic scientists and non-conformist scientists. My first response to Dr. Mizuno's results is to believe that they are genuine observations stated with honesty and sincerity. But when I think about how I'd behave if I had world-changing results, I keep coming back to this: barring some good reason, I would immediately hand my setup over to independent observers and begin working on a second copy. I would say something like this to myself: "while I know that I am honest, and I have seen these results with my own eyes, I understand that there seem to be many disbelievers, and so I realize that I will need objective outsiders able and willing to confirm the results I am seeing from my device in order to convince the disbelievers." I would not leave things in the hands of potential replicators, given that I could provide proof myself, even if only for one instance of my device.
If there were some good reason for which I could not find people who I would trust as objective and competent outsiders, I'd tell the world my reasoning.
Replication efforts are fine; it just seems like that basic first step has been skipped. If this were some minor result, I could understand that. But this is more or less the future of the world. If I had a device which heated a room on 300 W input power, when the room typically required 1kW+ to be heated, I would be paying people to come look, because I'd know that if I could demonstrate my capability to an objective outside observer, I'd save the planet, become vastly wealthy, and win the Nobel Prize. I would feel confident that by having an outside objective observer team observe my device, I could bypass any number of (hypothetical) academic scientists worried about their funding.
Perhaps this exact thing has been done with Dr. Mizuno's device, but those objective outside observers have also not been able to convince anyone. But I haven't heard about that.