althought makes sense? I mean you making more and more diplomatic action people are more ok with aliens
and its also making more sense for your goverment too since accepting it gives you better diplomatic options
From a gameplay perspective, all the different government ethos' are supposed to be equivalent - having one be consistently more popular because empires are engaging with half of the game (diplomacy) isn't balanced. It would make more sense to have only migration treaties increase xenophilia, and even then there is already an extra modifier for it just from having multiple species with full rights in the empire.
From a story perspective, I'm pretty sure xenophile empires go above and beyond just working with aliens, they are more like modern progressives who see integrating with aliens as a good in itself, rather than analyzing it as a means to an end. It's xenophobes who loathe to deal with aliens at all.
From a realism perspective, there isn't a correlation between a country making a trade deal with another country and their population wanting to live with people from that country, and certainly not the population wanting to live with people from every other country. It's possible it would make them more open to other deals, but that would rely on factors that aren't captured in gameplay, like whether or not the deal tended to benefit the different strata of the population.