Boycotting the game because of her comments is totally valid, but I don't think it would be effective way to send a message that her behaviour is unacceptable at this day and age.
In the end, boycotts would hurt more the hundreds of (until now) unknown developers working in this game for years, and, what is worse, the boycott itself might not even be recognised by the publisher, which might consider that "oh, we should have invested more on marketing since the sales were a bit less than expected".
In the end, I believe that we would be punishing more the (likely) 400 working on the game, directly and indirectly, in which 98% of them would really the money to make a living. Meanwhile, the one person that the boycott is aimed for, already is one of the richest people in the world.
Complaining directly to her and giving voice to the right people, for me, would be the way to go. I'm really glad that people like Daniel Radcliffe is taking a public stand against her comments, for example.
Edit: I just found out that the game is not even officialy announced. I was absolute sure that there was a AAA game being made by Warner and everything. Sorry if my post makes no sense because of it. :P