That's pretty asinine too. You're not allowed to advocate a different life than the one you're leading? It's like the people saying you can't promote a greener environment if you still own a car. It's just another way of shutting them up by creating ridiculous moral standards and acting like you've 'caught them' at an inconsistency. Life is full of inconsistencies.
It's also too simple to equate advocating wealth redistribution with needing to give away your money. Giving away your fortune is probably not the best angle for wealth redistribution. Certain rules of fairness for the wealth redistribution may be needed. For example, it may be useful to fight for rules that get all relatively rich people to join in (aka taxes), which will create a much more powerful push for equality.
It's also too simple to equate advocating wealth redistribution with needing to give away your money. Giving away your fortune is probably not the best angle for wealth redistribution. Certain rules of fairness for the wealth redistribution may be needed. For example, it may be useful to fight for rules that get all relatively rich people to join in (aka taxes), which will create a much more powerful push for equality.