Elon Musk buying Twitter is our prompt to leave

They get printed on the same page of the paper, but they have a different relationship to the newspaper itself. The editorial staff work directly for the paper, and have a fair bit of say in its operations.

This is a regular columnist. The news group didn't select this piece. They just ran the text in the (probably weekly) slot reserved for this columnist. They did hire her in the first place, but not because she reflects their opinions.

Columnists are hired specifically not to repeat what the editorial staff would say. They often represent a diversity of opinions. More relevantly here, they get to work independently: they produce their material without oversight of the editorial staff.

Their actual hiring structure can be complicated. They may be syndicated, or they may get their paycheck directly from the newspaper. But either way, they don't have any control over the newspaper's policy. The only power they have is to put words on the page -- an important platform, no doubt, but the newspaper doesn't have to listen to them.