What he calls conservatism is actually the Republican Party. It's a crucial distinction, and one he misses to his detriment. It's the Reagan-era GOP "big tent." It's not, necessarily, "conservatism."
Keeping this in mind, let's look at his ideas, skipping the first for now.
DON’T GIVE UP ON SOCIAL CONSERVATISM. BUT DON’T EMPHASIZE IT EITHER.
This is an essentially liberal idea: religion has a place in our society, but it isn't the overarching factor. The GOP, in its liberality, is able to talk to religious conservatives -- there's no need to scorn the religious. But they shouldn't be allowed to force their views on others -- marriage is a fine religious institution, but as far as the government is concerned, Rosen is exactly right: "it would ... mean dropping this absurd crusade against same-sex marriage altogether–while, perhaps, emphasizing the importance of traditional values in non-traditional family settings."
That should be the extent of religious participation in policy: we don't need to be so far left as to discount the religious, but the religious right does not have the right to enforce its religious views on the population at large. Which is a fine segue into:
DUMP THE DRUG WAR.
Small government, anyone? This is one of the crucial ideas of the Republican Party, and perhaps the one it has most blatantly forsaken. Telling the American people that this crusade is just as ridiculous, and ineffective, as that against booze, would be a grandiose and meaningful way of saying, "there are things the government shouldn't do. Here's one. We're working on the rest."
The last two of Rosen's provisions are more short- and medium-term strategy, and don't really bear in here. But his throwaway closer, "Also important: rehabilitating the free market, championing infrastructure reform, countering eco-hysteria while providing moderate yet effective energy solutions (plug-in hybrids, cap-and-trade, nuclear power, bicycles, congestion pricing…)," is also a big liberal cornerstone: it's based on respecting science and championing the free market.
I think he's confusing, in the same way he confused "conservatism" with "the GOP," the terms "liberal" and "the Democrats." It's a dangerous mistake to make, and does a disservice to the real ideas out there.
Salon wants to take back "liberalism" -- but the GOP is closer, and is the rightful heir to the title for reasons Salon lays out:
Because liberalism refers to a particular kind of social order, and does not depend on any implied relationship of the present to the past or future, liberals can be either progressive or conservative, depending on whether they seek to move toward a more liberal system or to maintain a liberal system that already exists. For that matter, liberals can be revolutionary, if creating or establishing a liberal society requires a violent revolution. Liberals can even be counterrevolutionary, if they are defending a liberal society from revolutionary radicals, including anti-liberal revolutionaries of the radical right like Timothy McVeigh or Muslim jihadists.
The GOP, in its true form, is very much an ideological defense of a liberal society against overreach. Let's get it back there.