I know we've discussed this several times, but I'm interested in seeing a poll breakdown of how people feel about his motives in this episode. It's really a fascinating episode that has led to a lot of speculation about Guinan's identity and powers, the nature of the Q and the evolution (as well as discontinuity) of the nature of the Borg.
1. As mentioned by a recent poster: Guinan's stance seems to suggest some kind of defensive capability against Q. Q also seems weary of her and refers to her as an "imp." They also mention an encounter from several century ago, and Guinan refers to other members of the continuum being "almost respectable."
2. The Borg's later assimilation/interest in organic material is not mentioned anywhere in the episode. Q says they have no "leader," (a notion altered by the creation of the "Borg Queen."
My interest in this thread, is more with Q's intentions.
Guinan seems to suggest that Q is a chaotic and immoral creature, and that he prematurely introduced the Federation to the Borg for virtually no other reason than to cause trouble.
Picard suggests that Q has done the "right thing for the wrong reasons." That while he motives may have been to cause trouble or "shake things up," knocking the federation out of their "complacency" may have actually been in the best interest of the Federation.
There seem to be other options not presented by Guinan or Picard. It's quite possible, actually (given the nature of Q in later episodes) that his action (while presented in a rather sensational way) was ultimately in the best interest of the federation by design
. When Riker gets angry with Picard about the loss of several crewmates during their forced encounter, Q uses the "bloody nose" metaphor to tell them that space is dangerous and that they need to be better prepared for it.
Forgive the simplicity, but I'm going to provide only three motives. Feel free to add a 4th or 5th in your reply if you feel it's necessary.
1. Picard's view: Q, in his trouble making, inadvertently did the best thing for the Federation-- though this was not necessarily his intention.
2. Guinan's view: Q, a menace, prematurely forced an encounter that shouldn't have occurred for centuries-- at a time when the Federation may have been prepared.
3. Additional opinions: Q, though a Loki-like figure in his presentation, was acting in the best interest of humanity by knocking them out of their complacency.