I am certain it was more because they wanted to protect you. If you do not know everything about it, then you are less likely to be targeted by someone looking for information.
[At least, that's how he would have done it. Plus, she wasn't actually a part of it, so he felt a little wary sharing too much information outside its ranks. However, he was aware from his time around the dome that Suzaku and Gino had been protective of Euphie. It wasn't a big stretch to make that part of his assumption.]