There is a link in the article to a more detailed description of the process. Basically, the viruses are used as a structural component that is then coated with metal. They claim the viruses are inert after the process but don't elaborate. My guess is that either the act of coating the viruses damages them, or they intentionally irradiate them somehow to damage their genetic material.
Obviously, production of large amounts of viruses in the wild would have to be tightly controlled. The problem with TMV is that you need to really grow the virus in a plant, you can't just grow a vat of the stuff in an industrial fermentation facility. TMV is used pretty regularly for research, so people do grow big quantities. Probably the biggest industrial virus production to date would be certain kinds of vaccine production. But those quantities are tiny compared with what you would need if everyone started using batteries like these.
Obviously, production of large amounts of viruses in the wild would have to be tightly controlled. The problem with TMV is that you need to really grow the virus in a plant, you can't just grow a vat of the stuff in an industrial fermentation facility. TMV is used pretty regularly for research, so people do grow big quantities. Probably the biggest industrial virus production to date would be certain kinds of vaccine production. But those quantities are tiny compared with what you would need if everyone started using batteries like these.