That link is about 2 years old.
The US government has become more active in wanting the general population to have enough supplies to provide for their own care, or shelter in place, during the gap between a disaster and the response of TPTB to the disaster, which is usually 3-5 days over here.
The "Zombie" adds were bouncing that need off the popularity of one TV series we have over here called "The Walking Dead", where survival is a daily battle in a post apocalyptic world.
Among the prepper/survival community over here the "Zombie" term has become synonymous with the concept of "sheeple that survived", making them a dangerous presence.
One major forum over here capitalizes on the term and is making some website managers wealthy. ( Yes people make money managing websites over here with income from advertising and "pay per link click")
Zombiesquad.com
https://www.zombiehunters.org/forum/