Wow. Wowowow. Let me start by saying that I have no problem with the Burlust being ridiculously aggressive in principle. It's been somewhat frustrating in past games to have them throwing themselves into the meat grinder too early and getting wiped out in retaliation... but this game was different. Not trying to turn this into an AAR but I do want to give some details. There is a tl;dr at the bottom.
Because of the new way that spacefaring tech drops work, I decided to just give everybody spacefaring right off the bat. The plan was to spend most of my time setting up moon colonies and trade routes and letting relations improve that way. I uplifted the Burlust seventh. Of course there's no Burlust word for 'trade,' so instead I decide to duel their homeworld warlord and get a good chunk of influence out of them early.
Mistake #1: uplifting Burlust when attempting a trade strategy. On their own, it would have taken them well over a year to become spacefaring.
I win the duel, but because of that nasty front-facing Burlust laser I played it quite safe, taking 60-70 turns. So about 1.5 months pass on the big map. In that time, the Burlust go straight for the Thoraxian throat. "No problem," I think, "I'll just use my newfound leverage to stop the invasion." I won't spoil the text of the Burlust response to this suggestion if you haven't seen it, but the bottom line is that the Burlust will not consider peace for the next 60 months - not because they hate the Thoraxian, but specifically because their last warlord lost a duel.
Mistake #2: assuming that the Burlust would be like any other government in having quick, clean transfers of power.
Well, fine. The bugs are going to die. Things could be worse. I continue my mission of trade, while also encouraging the other races to beef up their armadas. After the Burlusts conquer the Thoraxian homeworld, though, they immediately turn on the Andor. This is still the year 3000. Flying to their defense (the Burlust love me at this point so I can afford to smack down a few of their ships) I find that... I am useless. Because the Andor have no armadas left in orbit, I do not have the option to fly around shooting down Burlust ships. And of course the Andor have no ground game so they're doomed. And on and on.
So this is part of my problem. I get that some Burlust actions are disabled after a duel. Early on, they're fairly easy to win, and you shouldn't be able to just duel over and over to raise silly amounts of leverage. Beyond that, though, it seems to me that the point of leverage is "you better do what I say, or else." You'd think that this kind of influence would be more effective right after a duel, if anything.
TL;DR but the REAL issue here, I think, is the inability to come to the defense of races that are huddling in their bunkers (if they even built bunkers). I tried to indicate above that I understand some of my strategic choices were not smart, but early aggression appears to be possible from any race that thinks it has a military advantage. Keeping things from spiraling out of control in the early game should not be contingent on the weaker races being able to mount a defense. That's my opinion, anyway.