Voting for a losing candidate does not mean throwing your vote away or not having your vote counted. People who picked Palin as their #1 choice won against Begich. Their vote was counted and it went to Palin exactly as they wanted.
If you want to argue that there should have only been one republican on the ballot to prevent a 'spoiler' you'd have to take that up with the republican party
There it is, there's the thing they're really railing against. They wanted every Republican voter to vote for all of the Republicans, then all (or none) of the Democrats. Basically turning the ballot into RvD.
But they forgot one crucial thing: people. Even within the party, there are members and candidates others can't stand. And if you're going to give people choices, you have to be prepared for them to make choices you don't agree with.
If you want to argue that there should have only been one republican on the ballot to prevent a 'spoiler' you'd have to take that up with the republican party