Well, duh. More importantly is whether you see that as morally fair or as stealing. Usually when people say this line, they're implying that the rich will have all their money stolen until they have the same amount of money as everyone else - and of course this isn't actually advocated anywhere outside of communist societies.
That particular quoted line reminds me of a friend, who when she got a $10k raise, could do nothing but bitch about how 'half of it was going straight to the government' (despite it actually being only about 30%). If you define how wealthy you are by how much is taken from you, you should probably re-examine your priorities.
I strongly disagree with his apparent assumption that you can't "push down on the top" without wrecking things up. Sweden and Finland are proof that this isn't true, both have competitive economies that outscore the US in many important metrics for success (among these is general happiness).
You can let people become wealthy, and therefore give people incentive to invest and create, without creating the kind of insane inequality we currently have in the US.
His rant gets ridiculous, though, when he starts talking about doing away with the link between money and power... "We don't need to prevent people from being rich if we can prevent wealth from translating into power." That might be the dumbest thing I've ever seen a smart person say. Money is power. pg probably has someone mow his lawn. I can't do that. Why? Because pg is rich and can pay someone to do it, I am not, therefore I can't.
But that's not Power with a capital "P", you say. But it is. That's what power is, the ability to get others to do what you want them to do. If you have money, in a capitalist society, you have power, by definition. Whether you abuse that power, or use it for things that people consider to be bad (like buying off members of Congress) is a totally different story.
What implications does this have? Well, one of them is that money is, to many, a worthless thing to have if you strip away the power that comes along with it. Severing the connection between money and power would demotivate people the same way taxes do because, ultimately, they are the same thing: you used to have X, now you have X-Z.
In an ideal society, it would not be illegal to be rich. It would be illegal to buy off members of Congress, pay people to vote for you or your cronies, own media outlets and using them to get (and keep) yourself elected into office, or in any way use that wealth to subvert the democratic process. We don't have ideal societies, but that's obviously a direction worth going.
That doesn't mean you totally eliminate any power or privilege that wealth brings. Trying to eradicate malaria using your billions of dollars is an exercise in power, albeit not one that subverts the democratic process.
If I understand you, you're saying that wealth brings broad powers, and it's only a small subset of those (like political corruption) that are bad.
The rest, which are essentially power over the natural world (curing diseases, sending people to Mars, protecting ancient forests, resurrecting extinct animals) are good.
http://www.paulgraham.com/inequality.html
"So let's be clear what reducing economic inequality means. It is identical with taking money from the rich."