From that viewpoint, selecting Ryan as the vice presidential candidate is an enormously bold move and a major concession to what their very limited worldview tells them are the concerns of the grassroots. Ryan is more fiscally conservative than they are comfortable with. He is more of an initiator and policymaker than they feel safe with. He's effective enough that they find him somewhat threatening. From an establishment's myopic perspective Paul Ryan is an absolute flame breathing radical. He may not seem that way in comparison to Ron Paul, but most of them are not even capable of mentally accepting the ideological views which drive Ron Paul. They don't take his views or the views of those who support him into consideration at all, because they dismiss them as aberrant and outside of the political mainstream.
The idea of compromising with Ron Paul or making a concession to Liberty Republicans is absolutely inconceivable. It would be like pandering to cows or chickens. Only the most perspective among the party leaders have even noticed that the liberty movement can raise money and turn out votes, and even they have no idea how to court that constituency. In that position of uncomprehending ignorance the selection of Ryan represents what the establishment sees as an enormous concession. They can't imagine selecting someone more radical than Ryan and they assume that Ryan is such a strong libertarian (OMG, he reads Ayn Rand!) that he will make everyone happy, bring the Paul supporters on board, fire up the tea party and win over libertarian-leaning independents.
In reality the response in the grassroots has been fairly tepid. Some of the more sold-out tea party groups which have been taken over by the religious right are genuinely excited. But the more ideological groups and those who are real Liberty Republicans have reacted with anything from boredom to outrage. From the perspective of real radical activists Ryan is so close to the establishment norm as to be indistinguishable, just as from the establishment perspective he's far enough out of the norm to appear like a real concession to the radicals.
The problem with these two conflicting worldviews is that ideological voters are not likely to be terribly forgiving or understanding of an establishment they view more and more as a major part of the problem in our political system. We don't see what a huge concession Ryan is from the perspective of those in power, we just see how far he is from our ideals and feel disappointed. It's possible that this is not the right reaction. In analyzing any action the intent behind that action is enormously important. Yes, Ryan isn't what we wanted, but acting within their limitations, the selection of Ryan shows a clear intent from the establishment to offer a concession to the more radical pro-liberty elements within the party.