I don't believe that and here's why:
1. Just because they didn't vote on the ballot for office of president, doesn't mean they didn't vote for other offices on the ballot. Most Freepers will vote. (I am using the name "Republican" instead of "conservative" since a ballot has "Republican Party" on it and not "conservative".
2. When I was working in politics for a number of years, instructing in Texas Election Law, and helping put on Federal election primaries (held in spring/summer)and Federal general elections held in November), Republicans voted, they didn't stay home. I studied voting numbers and names of voters. I knew how many Republicans voted in the county due to looking at the numbers who voted in a Republican primary. I had their actual names. That same number, the same names, or more, voted in the Federal general election for Republicans.
3. It is a historical fact that Republicans will vote in every election, even if it is only for dog catcher. That is why, in a county, there are more Republicans than Democrats who vote in primaries and more Republicans vote in a non-presidential election year, and more Republicans vote in city elections and school board elections, and water district elections, etc. - hold an election for anything and Republicans show up.
4. Democrats will show up to vote in a Federal general election in a presidential voting year. They tend to know who is president but many don't know who their senators or representatives are. That is why Republicans have the advantage of electing their people in non-presidential years.
There are exceptions to these historical voting facts individually by person, as we are talking about individual human behavior. You may tell me you don't vote in city elections or some other entity election, but these historical voting facts are the general rule for all voters.
One has to also consider the makeup of the county when looking at the voter numbers. Take Austin, Texas, in Travis County. That county is a bastion of liberals so one would expect more Democrat numbers than Republican numbers in a primary or general election. The general rule of voting behavior, however, represents all counties in the nation.
If the Pubbies don't have a decent candidate, then I may just write in a candidate, or vote for the Constitution Party candidate.
We actually have some Dems around here that are Democrats in name only, and I might even vote for one of them if I happen to know them personally, and consider them to be honest and conservative. That's talking about the local elections, where the Pubbies don't even have a candidate running most of the time.