It's just a matter of fact that more than half of the US did not vote for this regime. You can object that more than half of the US did not vote for any president, and we would agree.
But in common parlance, it is acceptable to say that half the country voted for one or another candidate. It happens all the time:
https://thehill.com/opinion/4935813-trump-appeal-conservatis...
https://centerforpolitics.org/crystalball/how-the-other-half...
https://www.globalcitizen.org/en/content/voting-elections-de...
The center for politics and global citizen articles do not seem to use half that way though.
For center for politics the title starts with "How the Other Half Votes" and they seem to keep to that usage and never use half of USA/America.
For Global Citizen the title starts with "Half the Planet Will Vote This Year" an they seem to stick to that and never use half of USA/America
Another way in which Trump is incorrect is that his election victory margin is average among presidential elections in terms of both electoral vote margin and popular vote margin.
https://www.federalregister.gov/documents/2024/03/29/2024-06... https://www.cookpolitical.com/vote-tracker/2024/electoral-co...