What is so is that Karl Marx did not simply "like" Lincoln but also thoroughly embraced and advocated Lincoln's political cause during his presidency and the war.
Maybe Karl Marx liked vanilla ice cream too. Does that mean that if we eat vanilla ice cream, then we must support Marxism? What if Karl Marx liked women? Well, I think you get the point.
Actually, no, as your point rests entirely upon drawing a falsely constructed analogy. Your argument could easily be translated to the modern day with equally false implications. Doubt me? Consider this.
So Hillary Clinton likes Planned Parenthood. So what? Maybe Hillary Clinton likes hamburgers too. Does that mean that if we eat hamburgers, then we must support radical Clintonian feminism? What if Hillary Clinton likes women?
Though there is a strong theory that the last point may be true, surely you can see the difference that renders the analogy unworkable.
The fact is that Hillary Clinton thoroughly embraces and supports the political agenda of Planned Parenthood, just like Karl Marx thoroughly embraced and supported Lincoln's political cause during his presidency and the war.
Conclusion: I don't like Planned Parenthood and I like hamburgers. Hillary is totally irrelevant to this discussion and so is Karl Marx.