I think libertarianism should be principled. But liberals are statists not libertarians.
Libertarians are libertarians, and support abortion with zero limitations, restraints, or time limits.
There are no principles in the libertarian agenda.
Here is the leftists agenda hidden behind the Libertarian curtain.
Libertarian Party Platform:
Throw open the borders completely; only a rare individual (terrorist, disease carrier etc.) can be kept from freedom of movement through “political boundaries”.
Homosexuals; total freedom in the military, gay marriage, adoption, child custody and everything else.
Abortion; zero restrictions or impediments.
Pornography; no restraint, no restrictions.
Drugs; Meth, Heroin, Crack, and anything new that science can come up with, zero restrictions.
Advertising those drugs, prostitution, and pornography; zero restrictions.
Military Strength; minimal capabilities.