Why is it a good policy? Not to share with your listeners who you are voting for? I think that is dishonest. Think about it, maybe I’m wrong. But why shouldn’t we know who he votes for, when he keeps promoting conservative principles?
You said it yourself: "when he...promotes conservative principles".
Limbaugh obviously views himself as a spokesman for conservative principles -- but not as a partisan for any individual candidate. He assumes his audience can figure out the best conservative candidate for themselves.
I've been listening to Limbaugh for going on twenty years and he's never endorsed a candidate in the GOP primaries -- save once. In 2008, after Florida, I believe it was, but before McCain had locked it up, he endorsed Romney!
Gasp! But remember the choices at the time: Romney, McCain and Huckabee. You wondered whether he meant them or not, but Romney was at least saying the right things. McCain was actually insulting the conservative base daily. And Huckabee, playing a big-spending "compassionate conservative", had devolved into a stalking horse for McCain.
Limbaugh's intent was to somehow stop McCain, whom he saw as completely antithetical to the conservative cause. Didn't work.
I can't complain about the endorsement of Romney because, after Fred Thompson dropped out, that's where I ended up, too. For the same reasons.
At any rate, I believe Limbaugh is confident that his audience isn't going to vote for Romney. It's up to us to decide who we favor as best able to carry the conservaive banner.