OVH isn't responsible for what people do with the servers. They provide the initial installation, networking, hardware monitoring and some management tools, but that's it. If they detect that a server is sending too much traffic, they can guess that it has been hacked, so what they usually do is disable it and notify the owner to fix it. But they don't do more, that's not their business. If you want a host that does more for you, it's managed hosting you want, not a dedicated server provider.