[brenschluss]

Incorrect. Grammar, like all aspects of language, are socially generated. Currently, the shift has been to move towards 'she' or 'they' as a default gender.

Saying "'he' is grammatically correct" is like saying "C++ is the proper programming language." It's all about usage.

[mikeash]

And "he" as a gender-neutral pronoun is still quite common usage, thus still correct by your definition of it.