I think it's incredibly rude to ask a woman to speak about her age, and she has the right to create a back story, as a Hollywood actress. Rebel's career is founded on her ability to become different characters and portray them in a believable way, I don't think this is any different. What does it matter, if she's 35 instead of 29?
Rebel Wilson, lied about her age for many different reasons. I really don't think anyone cares that she is thirty five, not twenty nine, I know that I don't care at all. Rebel is who she is and no more. She wants to keep her fans happy and glad. So!
No, one's only real concern should be her acting ability. Plus, people should focus on their own business. As long as she acts well and portrays her character well, nobody should worry about how old she is. Let her live her life as she likes, and worry about your own business.
Whether she is 25 or 35, her acting skills are what people are concerned with. Her age should not be an issue, as she has gathered a rather large fan base thus far, and her age should not affect any of her fans or anyone who is interested in her abilities.