All of you folks who voted Libertarian or Green should take note that it looks like Florida, Virginia, and Ohio are all going to be decided by margins much smaller than third party candidates took.
I won't presume to know which way third party voters might have voted if they had stayed within the two party system, but it's pretty clear that they could have swayed the election if even a portion of them had stuck with Democrats or Republicans.
I'm in a swing state (although not one with a small margin like you mention) and I'd rather vote what I feel is right than something I feel is wrong, regardless of if my one vote would have changed the main outcome. I won't compromise myself that way. Others may feel different.
Also what about all those folks whose vote doesn't matter anyway (someone voting Romney in California, or someone voting Obama in Texas).. there could have been a LOT more voting third party where it wouldn't have any effect other than possibly getting the third party to 5%.
And finally, what you state isn't even true for most of the swing states (Nevada, Colorado, etc.) and not even true for two of the three you mention (Ohio and Virginia). It looks like Florida may be the only case where it is correct, and then by only .2%? The numbers I'm seeing are Obama 49.8, Romney 49.3, Johnson 0.5, Stein 0.1, Barr 0.1.
So in almost every case, and nearly in that one as well, your argument isn't true, and shouldn't be used to try to encourage people to stick with a two party system to our country's detriment, IMO.
BTW, congrats on your state passing two very progressive ballot initiatives.