You can say whatever you want, but no one is listening. Voter turnout is so low that the signal of voting 3rd-party is completely lost in the noise of passive non-voting. 3rd-party votes might feel good, but pragmatically (and what is voting except a pragmatic attempt to advance your preferred policy), they are useless.
I encourage everyone on this comment chain to read Clay Shirky's "There is no such thing as a protest vote" [0], and really take it seriously, instead of jumping to thought-terminating cliches by angrily denouncing him as a sheep or whatever. He's right.
[0]: https://medium.com/@cshirky/theres-no-such-thing-as-a-protes...