Having been to Vietnam where the US pulled out and the Stalinists imposed their system, and South Korea and Taiwan where the US backed regimes survived and eventually liberalised I'd say she was dead wrong.
The South Koreans in particular are very lucky there wasn't an anti war movement in the US during the Korean war. If there was the South would have been annexed by the North and they'd be living under Kim Jong Un's crazy regime.
Or look at Vietnam. The boat people refugees fled the south after the war ended. So clearly a peace where they were ruled by the north was actually worse than war.
Hell as a Brit I'm very glad the WWII equivalent of the anti war movement the German American Bund didn't have as much success as its Vietnam era equivalent
The German American Bund, or German American Federation (German: Amerikadeutscher Bund; Amerikadeutscher Volksbund, AV), was an American Nazi organization established in 1936 to succeed Friends of New Germany, the new name being chosen to emphasise the group's American credentials after press criticism that the organisation was unpatriotic. The Bund was to consist only of American citizens of German descent. Its main goal was to promote a favorable view of Nazi Germany.
The parallels are pretty striking. Both the German American Bund and the Vietnam era anti war movement were openly in favour of a totalitarian movement (US anti war demonstrators carried Vietcong flags, and the AV carried swastikas) and their main aim was to allow that movement to overrun a country friendly to the US but they disguised that as being in favour of 'peace'. In Vietnam they unfortunately succeeded in that aim.
If the AV had been as successful as the Vietnam era anti war movement the US would have stayed out of WWII and the Nazis would have overrun all of Western Europe and the UK.