You have their platform statement, you've seen their attempts at justification in this thread.
Fair debate and honest expression of differences on politics are hearty institutions on this forum. Expecting either side to be totaly consistant in internet dialogue is ridiculous. Should I hold you responsible for inconsistancies of every poster who sides with you? Certainly not.
The historical record is clear. The Federalists ignored the cautions of the Anti-Federalists and the continuance of slavery and the eventual civil war made the 13th a politcal remedy. LOL, libertarians are politically mad, IMHO, for lots of other reasons but some word games here don't do either side any justice.