I left the UP once, when they passed a law mandating "Empire" as a government choice, despite the fact that I was roaring along with a full-blown Federation by that time. I decided that the hit to my economy from falling back to Empire would be a lot more damaging than the loss of my Trade revenue, so I left.

And, yeah, there was no going back; what was even more annoying was that I wasn't even allowed to trade with the Minors -- who aren't even members of the UP! Grrrr.

Why not just take out the Iconians? Like any other random event I find that UP votes sometimes force radical changes in my strategy, but I don't really think of that as a bad thing.

Update;

Ok i managed to find an earlier save than the UP vote and replayed everything again.

Currently i am dominating over the AI, my ships are by far the most powerful around and it helps that i am the only race using missiles and the second larget hull!

I took out the drengin empire and then declared war on the drath. The yor think they are much stronger than me and demanded tribute - which is funny because i could destroy their entire fleet with just one ship! So they just declared war and i will be annihilating them soon enough.

All this is happening on masochistic level and i havn't even built any factory starbases yet! So i am now beginning to realise that i didn't need to replay the game because of the UP vote after all! (in consideration that i have about 6 mining starbases and so whatever effect they have now would be severely reduced).