You know, this would've been the perfect time to tell the prince/imperial family about Collette being a demon, her credibility is pretty high right now, there's a person unrelated to her claiming to have been affected by a mysterious phenomenon and her father would most likely support this claim.
Also, by telling now she could've helped this innocent guard who is probably going to lose his job.
"If she goes to war and wins she'll be looked at as a hero and won't be shunned anymore" You mean like the first hero, the tyrant killer, founder of the land, and king-maker who you garbage people ostracized so hard he ended himself? His people probably didn't even reward him after all he did, yeah I'm sure history won't repeat itself *eye roll*. I know everything went well, but realistically that was a dumb ass excuse.
Also, fuck her parents, oh she went to war and she's white now (which is a whole thing in itself), let's make amends. Ugh, so happy she told them to fuck off.