Powell is correct, there are probably GOP leaders who are afraid to publicly disagree with Rush Limbaugh. Whether this is good or bad for the GOP probably depends on the issue of disagreement.

There are probably some not very fiscally conservative GOP politicians who are scared of Limbaugh for good reason, they are as wasteful with money as liberal democrats.

There are probably some not very socially conservative GOP politicians who would gain little from challenging Limbaugh, even if he is wrong. This unfortunately does not help the GOP, as it allows a barrier to continue to exist between the modern GOP and those with more moderate or libertarian social views.