Trisquel is not basing Ubuntu off a “non-free” distribution. Trisquel is
based off a distribution which has included non-free software without the
non-free components.
To add to this Ubuntu, LinuxMint, and other distributions are made almost of
entirely free software. Trisquel is not promoting Ubuntu, Debian, Linux Mint,
or any other distribution which includes non-free software. Trisquel does not
link to any of these distributions. Trisquel does not link to sites which
include information on non-free software either.
Why it is based off the free parts of Ubuntu is because it is well maintained
and targeted at desktop users. The same as Trisquel is. This is a good
example of cooperation on something where two sides with two different
perspectives on things makes a lot of sense. There should be more of this.
Not less.
This cooperation means that a lot of bugs get fixed, patches applied, in
Trisquel. Many of these improvements (all free software) are not applied to
Debian. Debian is geared more toward the server than the desktop. It has very
long release cycles, testing phases, etc.
Trisquel is not using the non-free portions of Ubuntu though. Canonical does
not introduce new non-free software to the distribution either. Neither does
Linux Mint. They are including third party components for which they have
little or no control over.
I'm not a fan of distributions like Linux Mint including non-free components
because it gives companies the perception of non-free software being ok. If
it is ok then they have fewer reasons to release the source code under
acceptable free software licenses. The argument becomes one of a purely
technical matter. That is mainly that free software works better, integrates
better, etc. This is a good reason although not as good a reason as the
ethical. People have to be ethical if they want to force corporations to do
the same.