GNOME is not one program. It is a set of programs. GNOME Shell is one of
them: GNOME's user interface. Trisquel is a set of programs too. Some of them
are GNOME programs (e.g., the GNOME System Monitor) and some of them are not
(e.g., LibreOffice).
Individual programs are "packaged" so that they are easily
installable/removable through a package manager. A program usually needs
other packages to work: other programs that it executes, libraries (pieces of
software needed by several programs), fonts, etc. Those are called
dependencies. If you install, from the package manager, a program that
depends on other packages, they will be automatically installed as well
(otherwise the program you want would not work). If you remove, from the
package manager, a package that is a dependency of some programs, those
programs will be automatically removed as well (since they would not work
anymore). In both cases, the package manager first lists the whole list of
packages it will install/remove and asks for a confirmation.
Sets of programs such as "GNOME" or "Trisquel" also relate to packages
("gnome" and "trisquel"). They are called "meta-packages" because they do not
install anything by themselves. They only depend on other packages: all the
programs in the set (the whole GNOME desktop environment and Trisquel's
default system), which therefore becomes easily installable at once.
If my last two paragraphs were clear enough, you should now understand that
removing a program in Trisquel's default install automatically triggers the
removal of the "trisquel" package. It is no big deal because "trisquel" (or
"gnome" or "trisquel-recommended" or ...) is a meta-package: by itself, the
"trisquel" package does not install anything. Removing "trisquel" only means
you will not have the whole Trisquel's default install anymore. Notice
however that it also means that, upgrading to Trisquel 8, you will not get
the new applications added to the default install, i.e., added as
dependencies of the "trisquel" package.
