1. Abe's criticisms of the two leading candidates are indeed hilarious and pungent, but all his arguments against Hillary are about how she's "crooked" -- nothing about her ideology. She originally achieved mass unpopularity because of how far left she was, and it's really worrisome that things have shifted so far left that that's no longer a safe line of attack. I just can't see liberals caring much about the kinds of "crooked" stuff she has plausibly been accused of.
2. Abe wasn't exactly a third partier -- he was a Whig until the Republicans formed in the wake of the Whigs completely breaking down and fracturing. But it's a valid point that even political parties aren't forever: they can die like the Federalists and then the Whigs, and new ones can form and become major parties, like the Whigs and then the Republicans.