I think that he is part of a growing list of people who were Democrats, and have become disillusioned with where the party is going nowadays. Many of our top government people were Democrats before they left the party.
President Trump, RF Kennedy, Elon Musk, and several others have either changed to Republican, or simply gone Independent. The party does not even treat their own people well.
Look at what happened to Biden, even.
They installed him as a president, knowing that he was terminal with dementia, and ran the government around him, leaving him to take the blame for anything that went wrong.
Then, without any kind of primary election, they dumped him and brought in Kamala Harris, whom no one liked prior to that time. This was their top person, their chosen president, and this is what they did.
Kennedy could have possibly won the election for the Democrats, but they stopped him from even running in the primaries as a democrat. The Kennedy family has been one of the biggest families in the party since JFK in the 60’s.
How could anyone feel safe being part of this political party anymore ?