The correct solution to this problem is to abolish the distinction between capital gains and ordinary income (ie wages), and abolish the corporate income tax that justifies the "double taxation" argument that justifies the capital gains rate. Capital gains is why Mitt Romney can make 200 times as much as I do in a year, and pay half my effective tax rate. This is broad across the economy. It's a fundamentally immoral…
I would argue that income tax is immoral - the more you care and provide for the society - the more you are punished for it. Only fair tax I can think of is a poll tax, where everyone pays the same amount regardless of their income. With this model you could think of giving 100% discount to those who can't afford it.
If marginal tax rates exceeded 100% you might have a point. Not to mention the implicit bizarre self-righteous assertion that income correlates directly with "caring for society". Tell that to fire fighters, EMTs, teachers, and disaster aid workers.
But I guess "marginally, the more you convince others to part from their money, the less you directly benefit from it" doesn't quite get the objectivists as agitated.