FreeBSD Ports CVS End of Life on February 28th 2013
freebsd.org
freebsd.org
Normally when someone brings up git on the lists, the common response is simply, "there's already an official mirror[2]". SVN fits the FreeBSD development model -- everything is centralized.
Moreover, it can be argued that when the decision was made in 2008, DVCS's weren't as well-known as they are today. The relative maturity of SVN I believe was a large factor in the decision.
--