Earlier quoted context omitted.
Yes this stood out to me too. I don't really understand why a warrant would enable alteration. Copying I can wrap my head around, but alteration without oversight seems awful. Hopefully the warrant has more fine print than the journalist implied.
Probably legal completeness. Think about it, log in to a windows computer there is probably an event log that gets updated. While checking browser history the history may be altered. Installing surveillance applications would modify the machine. Etc.
Isn't this a huge problem? That the police can forcibly install surveillance applications in a news organizations computers.