Funny enough, all this means that of all the civilisations in the 40K universe, Eldars are most likely the least evil of them if we base this on the gouverments treatment of its own citizens.

The third option is that Farsight somehow discovered that his entire race have been turned into Eldar puppets, and has escaped servitude in order to instigate a rebellion of some sort.
Really?, i didnt think there had been any official contact between craftworld Eldars and Tau.
At least i could find no mentioning of such thing in the current Tau codex, and according to the map they lies in opposite sides of the galaxy.