I'm not saying a role contest should be giving out flaws, but at the same time, I do agree if your role says XYZ, but you never RP it and do nothing to reflect it, the Role is bullshit.
I'd give a flaw out to someone for that too, but I'd probably give them a note saying hey, we loved the role, but we noticed you char is obsessed with (I'll go with my char) breaking a curse. Well, we're giving you the ancestral curse flaw to reflect you're cursed existence, but through your RP you'll be able to remove the flaw, and be rewarded additionally beyond the flaw removal.
So maybe I'd grant a flaw with the understanding of I'm using this as a role device for you, and if you follow through with the RP consistently then you'll get rewards.
Opportunity lost, maybe. Thought without any explanation, I'd be a little annoyed too.