Here is how I interpret the saintess in this chapter. The misandry she exhibits is of the level of a 10 year old girl who is not ready to be interested in men romantically (cooties...need I say more?). This is in keeping with her apparent young age. I would never call a young boy getting creeped out by girly cooties a mysoginest because it is a phase of gender and sexual development that most young children go through.
She may well be interested in men in the future since she admitted that the prince is good looking, and her comment about his personality was on point.
If she were portrayed as an older teen or young woman I would see her comments as a big issue, but for now she is simply venting frustrated feelings to the one person she is allowed to be herself around. Yes this makes her act more like a brat because she has had to suppress herself so much in the role of saintess.