He's right, but he's also being nitpicky about rather irrelevant details. The point being made was about popular support for the president (or lack of thereof) and their ability to get it; in that regard it's the popular vote, not the electoral college that matters.
And Bush Jr. didn't "barely achieve a plurality" - he outright failed to achieve even that. Gore had the plurality of votes, but Bush Jr. won the electoral college (note that I'm not saying anything about the legitimacy of either as president, just nothing that in comparison de Gaulle had a popular support landslide). There were three other such cases in US history. In addition to which we have a further 14 cases of a candidate being elected president with the most votes, but less than 50% of the popular votes, including some who won by the narrowest margins (Garfield in 1880, Kennedy in 1960), and more who won by less than the 3% margin between the Gaullists and thei closest rival party in the 1958 legislative election (Nixon in 68, Carter in 76, Bush in 04, who had a majority but a lower margin...)
It's also worth noting that these are the results of CDG's supporters in the legislative election, so elections that were only indirectly about de Gaulle himself. The first presidential election was not done by popular vote so doesn't really tell us much, but his second one in 65 was a clear victory with no "barely" about it)