To begin with, even if he somehow became braindead and wanted to rejoin the 'hero' party, the morons would probably demand he give them a lot more loot, be a porter or whatnot.
If Missha actually had any good feelings for him and was hopeful to start a relationship, then she should've done something other than agree with the two morons who were out of their minds ,logic , common sense and morals. Unless of course she was bound by some method to be magically forbidden from saying something like that, then she could've given other signs.
Frankly, the only 'real' reasons for her refusal to actually show her feelings for him that would be accepted is if her mind was forbidden or controlled into doing it, anything else she could've bypassed in some way.