Don't worry people. Trisquel 7 is based on Ubuntu 14.04 LTS (Trusty Tahr.)
The whole "using systemd as an init" didn't happen until this past March for
Ubuntu 15.04 (Vivid Vervet) (and really then was only for upgrades since
Vivid was released in October with upstart.) But remember that Trisquel is
only based on LTS versions, and the next Ubuntu LTS will be 16.04 (no name's
been announced, AFAIK but it'd be Trisquel 8.) So those that wish to avoid
"systemd as an init" have until at least April 2016 and really longer because
there's usually a multi-month delay before the corresponding Trisquel version
comes out.
Even then, Trisquel 7 is supported until April 2019 so people that wish to
avoid systemd as an init could remain on a supported Trisquel 7 until it
becomes EOL in April 2019 so that's like 4 years away still.
So don't worry about it. :)