They still retain all of your messages (including DMs) unencrypted indefinitely with no easy way to remove them. Deleting your account doesn't remove messages either.
> The nothing to hide argument states that individuals have no reason to fear or oppose surveillance programs, unless they are afraid it will uncover their own illicit activities. An individual using this argument may claim that an average person should not worry about government surveillance, as they would have "nothing to hide".
> Edward Snowden remarked "Arguing that you don't care about the right to privacy because you have nothing to hide is no different than saying you don't care about free speech because you have nothing to say." He considered claiming nothing to hide as giving up the right of privacy which the government has to protect.