Yuna's own siblings want to take her out. She has to be sure Ijin isn't some pa** or part of a scheme to bring harm to her. The only reason they are on alert is Ijin wasn't on their initial data of what to expect when they returned which was further amplified when his background doesn't match what the records say. Also, Ijin dealt with a very difficult opponent (in terms of similar power to their base). Their reactions are perfectly normal.
Their alert should settle down unless they too have harmful intentions to Ijin's family, though that doesn't appear to be the case