Greed is Good (In the Appropriate Context)
I would strongly, strongly, strongly caution liberals against making non-greediness some kind of core political virtue. There's a certain strand of self-regard, a shortsighted meanness of spirit and neglect of public purpose, that's incompatible with the spirit of modern egalitarian liberalism, but mostly the whole point of the enterprise is to convince people that liberalism will make you better off.
I go all metaethical on his ass
Greed is bad (but don't say it out loud)
You are arguing that liberals should not say that greed is a vice. Your point is that, while few people have Ivan Boesky levels of greed, most people would like to have more money and it is bad politics to insult most people.
This does not mean that greed is good (in the appropriate context) it means "We should say that greed is good in the appropriate context." which is a different statement from your title.
I don't think people can make something a virtue, political or otherwise. I think either non-greediness is a virtue or it is not (notice I believe in ontologically objective moral truth).
In particular, non greediness is a virtue ceteris paribus. I personally am to lazy to be greedy. This is not virtue, just another vice. People who are industrious and thrifty but not greedy are virtuous. The three traits can be reconciled with a budget constraint because they give money away.
All arguments that greed is good in some contexts are consistent with giving the proceeds away (Brad as usual wrote this better).
I would have to lie to say that the ideal person is greedy. I would be willing to lie for the cause, but since no one cares what I think, I'll just say greed is bad.