Eric Martin makes an important point:
As previously argued, the notion that our military intervention against a despotic regime (that we had never supported to begin with) would somehow convince the Arab street that we don't back non-democratic regimes in the region when convenient, was a highly dubious contention. After all, even if we did intervene in Libya on the side of anti-regime elements, we would be continuing our support for often brutal, non-democratic regimes in places like Saudi Arabia, Bahrain, Jordan and Yemen - with the jury still out on how Egypt tacks.
Opponents of intervention were characterized, to use Peter Beinart's telling, of "immoral consistency." Aside from the fact that one need not be opposed to intervention in all circumstances to have doubted the wisdom of intervening in Libya, one intervention on behalf of an Arab populist uprising was never going to make people in the region forget about everything else they hate about U.S. policy in the region. No one's arguing that the U.S. should treat every country in the region exactly the same, but the public relations benefits of "moral inconsistency" in Libya were oversold.