(I did the cinnamon install and I don't have nautilus).
Welcome to the light ;-)
As the default `xdg-open %d` opens a file manager then thats safe, it won't open some random software on the users system. If they change the setting they are responsible for the consequences.
So my opinion is that `xdg-open` looks to be a better more portable (among Linuxes) alternative to `nautilus` and its ok to merge, although give the weekend at least for others (with non LM distros) to look at it.