It always cracks me up when this is used to justify genetic tinkering. I'm completely pro-tinkering, but this is obviously a case of picking a good possibility from a myriad of both good and bad.
They could easily have said "The accomplishment might eventually lead to organisms that reduce our bones to jelly and result in the ruination of all that we hold dear."
I mean, it's possible, right?
Yes, but it already happens, naturally. Some viruses and bacteria cause illness and reduce bones to jelly and we need to a) find out how that happens and b) stop it. Knowing how they work may increase the number of custom, dangerous viruses possible, but it's not the only way to increase the danger. We could do nothing and some militant group with some reason to hate some people can harvest a dangerous virus without any knowledge of biology at all, and still infect people. And again, it could just happen naturally. Viruses cause many health problems and disease, and we're just beginning to understand how many problems, from cancer to birth defects, are caused by viruses.