I believe they want to clear domain name. I bet they didn't check if the domain name before going to new title of the game, so their commercial management got caught in problems (which they solve form the position of pure force).
However, warzone is not original name on the internet, and there were few games released earlier with the same name including some board games and a book. Before changing domain name to warzone com, i.e. from warlight.com, there were also some conflicts with earlier users of the name (a book, now I see only second book with same name from different author).
Right now, warzone on the google.com is first sponsored choice. But, name warzone is mentioned several times on Wikipedia -
https://en.wikipedia.org/wiki/War_zone and there is no mention of this game there, so, I guess, there are maybe even more uses of the same name.
I don't know how far Fizzer wants to keep with the issue, but, it may be too demanding and would drain too much time and resources.
This conflict is also mentioned in my country's PC magazines (with correct facts).