Actually, that's not true You can extract it on Harmattan or ubiboot console. As long as you do it as root you do not need the "--numeric-owner" option.
sudo tar --numeric-owner -xf nemo-handset-armv7hl-n950-*.tar.bz2 -C /media/Alt_OS/
devel-su rootme tar -xf sailfish(or nemo).tar.bz2 -C /Alt_OS/