Xenophobia is the word you're looking for. As for stopping it - I hear you but you can only control you and respectfully, she's a fictional character designed to be a protagonist this season. Chance of come-uppance; high. That said, to stay n character ourselves, we have no way of understanding two things: 1: her past experience with the Eliksni, who have (in general) been trying to destroy humanity since arriving in Sol. 2: current influences to her opinions from sources she is close to, either inside or outside the city, as it's rumored the FWC is under Savathun's control. We've seen some good done by some Eliksni recently but being fair, they've shown themselves to be a brutal and at times overwhelming enemy to the last city for hundreds of years. The kind of emotions that go along with that are usually not able to be simply pushed aside and would make her character far less credible if they could. Remember, she's not the only one uneasy about this alliance, many are wary on both sides no doubt but the Vex pose a bigger threat right now so that's where the focus is. Enemy of my enemy and all that...