There is an effort to genderfy Mediawiki messages but we require gender minded users an extra effort to set his/her preferences in all projects. It is supposed that a gender of a user should be unique across all projects.
An interesting case where hopefully nobody would want different values on various projects. Maybe this could be the first global-only pref, putting in place the framework for more to follow.
The only possible objection I can think of is someone might prefer to be gender neutral in some languages only due to language specific implications, such as the gender specific terms not being ideal due to simplification in the implementation.