It's wishful thinking to suppose that a more technically advanced civilization would be more peaceful and tolerant.
I don't think so, for two reasons.
The first is that our own history is one of increasing peace and tolerance. If you don't believe this, you should read Stephen Pinker's "The Better Angels of our Nature". I won't attempt to restate his arguments here, but there's very compelling evidence that we've become dramatically less violent and more tolerant in step with our increased technology.
The second is that advanced technology is impossible without extremely high levels of cooperation. For one example, the massive, interlocking global supply chains that are needed to produce all of our more advanced technologies today (such as the computer I'm typing this on or the phone sitting next to the computer) are mind-bogglingly complex and involve a significant fraction of the world. Broad negotiation and cooperation requires empathy, the ability to understand the minds and goals of both your collaborators and your opponents, and that same empathy slowly -- but inevitably -- results in discomfort with violence and suffering.
Indeed, we've become uncomfortable with violence to and suffering of even non-human creatures. Up to the 19th century cat burning was a popular mass entertainment in much of Europe. They'd hang a sack full of live cats over a bonfire, or douse a cat in oil and light it's tail on fire and chase it through the street. Although there were people who found these activities distasteful, the vast majority found them hilarious. Today, that would be reversed, and the vast majority would call such "entertainment" sick. In many jurisdictions, such animal cruelty is a felony.
It's clear that we're rapidly proceeding further down this road. We devote large areas of land and resources to preserving other species. Vegetarianism and veganism are on the rise, and I expect that within a few decades we'll have good cultured meats and that we'll virtually cease killing other animals for food. As the human population declines (it's rising towards a peak but will then begin to fall) and our wealth increases we'll be better able to indulge our empathy and go ever further to minimize future killing and we'll work hard to try to repair the damage we've done to other species.
Your argument is that it seems likely that advanced alien species would have followed much the same course that ours did. I agree, I think it stands to reason they'll have followed that course to become very peaceful and tolerant, particularly if they have achieved FTL travel which should completely eliminate any need to compete for resources. To reach the stars (assuming that's possible) will require openness and scientific inquisitiveness that are incompatible with violence and subjugation, and make them unnecessary.