I accept reality, the only thing third parties do is split the right or the left vote and let the unsplit faction win. As long as we have the winner take all electoral college system, we can only have two viable parties.
The problem is whose votes will they predominantly drain. Canada had the situation for several elections where the conservatives essentially split into two parties and they shared the conservative votes which gave the Liberals the plurality in sufficient ridings that they controlled the government.
It sounds like these guys, like the Greens would primarily take Democrat votes giving the GOP a boost in the same manner. In the long run, I believe 3 parties are a better way, but getting there can be ugly.