Earlier quoted context omitted.
> If you vote third party in this election, you might not win this time, but you can start laying the foundation for a strong third party to emerge in future elections. Assuming that there are future (fair) elections. I have serious concerns about that if Trump is to become the president. I've heard many people on the right having the same concerns about Clinton.
Improvements to the fairness of elections won't come from those who benefit from the status quo, it'll come from those at the grassroots level. Boosting the electoral performance of third party candidates builds confidence that grassroots movements can make a significant political impact. As for whether Trump or Clinton would actively block fair elections, that wouldn't surprise me, but I wouldn't put it past either…
I would dare say that these two things aren't equivalent.
Clinton "rigging" the primaries didn't involve preventing people from speaking out, or excluding them from voting. It was mostly about the system itself being "pre-rigged" by design, so to speak, and then some coordination with the DNC behind the scenes. All bad juju, but not the kind of thing that causes lasting damage compared to the current state of affairs. Compared to Democrat "machines" of the old, it's practically peanuts - and the country and its political system survived those.
OTOH, Trump's talk about expanding the libel laws and otherwise targeting the press, if implemented to its logical completion, would take a lot of time to dig out of. That's not even taking into account his threats to "investigate" his political opponents if elected.