That's half of the answer, yes. The other half is that the legacy media outlets were livid that a small newspaper like the Mercury News broke such a massive story. One that they had dismissed for many years. Institutional media traditionally sets the news and the narrative framing those events - like letting the rest of the media know HOW a story should be told and therefore are the gatekeepers of the news. They are the opinion makers and they truly believe that their voice is more legitimate than all others.

Yes, attacking a journalist in this manner was absolutely against the spirit of actual journalism. At the same time, it fits the behavior of corporate newsmakers deciding on what's fact and what's fiction.