Ron was a purest libertarian who you are right about
Rand is a pseudo libertarian who is somewhere between neo-con and libertarian but scares both groups away, decimating his support
I think Rand is just as Libertarian at heart..he was just young enough to take his father's advice to act Republican earlier to see if he could be seen as a legitimate R while completely inheriting Ron's Libertarian base. Instead, he has support of neither.