What you just said made no sense. You're saying that "precisely the situation where you'd be even more inclined than normal to use 've'" is the situation where you know the gender of the antecedent.
To the list of reasons not to torment your spellchecker, add that.
I lump usernames in with proper names. I guess if you don't lump them together, it's not precisely the situation. But I still feel like I can use that article as validation for not wanting to use 'they' in certain situations.
e.g. (if I didn't know your gender, like I don't know most genders on HN), I'd much prefer "tptacek said that ve likes bcrypt" over "tptacek said that they like bcrypt".
To the list of reasons not to torment your spellchecker, add that.