fantastic. ubuntu mate is throwing a fit and wants to remove ubuntu-mate-core and ubuntu-mate-desktop simply because i do not want mate-screensaver and want xscreensaver instead
so looks like the rest of the mate packages are already set to manually installed so removing ubuntu-mate-core and ubuntu-mate-desktop did not add anything to be autoremoved, thankfully
here it is again in 2016 similarly unsolved https://ubuntu-mate.community/t/nasty-problem-with-ubuntu-mate-desktop-ubuntu-mate-core-etc-dependency/6827/25