The official statement:
"'Rubicon' gave us an opportunity to tell a rich and compelling story,
and we're proud of the series. This was not an easy decision, but we
are grateful to have had the opportunity to work with such a
phenomenally talented and dedicated team."
I liked the show, at least at first, but did not stick with it. At least one viewer I know of who did was constantly driven crazy by it. He will not be pleased that there won't be a second season to tie up storylines. Especially when AMC has embraced zombies instead.