This makes sense. What never makes sense to me is when people worry about viruses from ice cores that are a billion years old. Because it works both ways: viruses have to be pretty well adapted to you in order to harm you. There are no such viruses long before humans even existed. I’m sure there are exception, as with viruses that manage to jump species, but I wouldn’t worry much about viruses from before the time of mammals, yet some people freak out MORE the older the ice core is. They’ve seen too many movies about ancient evil escaping old crypts.