It still calls itself an MMO in its Steam description:

The Day Before offers players a uniquely reimagined journey into post-apocalyptic open-world MMO survival set in the present day on the US East Coast following a deadly pandemic.

In this particular instance the journalists are doing their job. It was advertised as an MMO. They could change it to “so-called zombie MMO” or something, but that wouldn’t be as neutral as the current title.