Geez. The human experience with imperial and mercantile expansion depended on trade of goods in and out of, and emigration from the home country or in some cases with the absence of the latter, the existence of indigenous elites and conflicts that could be manipulated to your own interest. You don't go to war with the 'natives' for whatever reason, unless you know you have, along with the population base, the advantage of superior technology and the support if needed of the home country. And in the absence of goods (or people) that can be traded with the home country the motive for acquisition is pretty limited (gold doesn't have an 'intrinsic value').
I doubt that the explorers in MEA will have that level of connection with the home GALAXY. You could see the explorers become involved in a conflict internal to Andromeda, but I can't see that their interest would go much beyond alliance for their own protection and survival.
Edit:
Google 'metis' as a example of what happens when outsiders depend on locals for their survival and prosperity even where there was trade and exploitation of local resources.
Another factor I think is that ____ spaceship will likely have a mixed crew, a lot of different species and religions -- to the extent these are visible -- working towards a common goal. You would tend not to see the race and religion based extremism in attitudes that were at least a surficial characteristic of the Old world dealings with the local population. The spaceship would tend more to be the Canada that Trudeau and Chrystia Freeland envision.