For those who saw it as a sign of unity, Biden's gesture was a way to show that he is willing to work with anyone, regardless of their political affiliation, to make the country better. They argued that the 9/11 attacks were a time when Americans came together, and that Biden's wearing of the Trump hat was a way to honor that spirit.
For those who saw it as a betrayal, Biden's gesture was a way to appease Trump supporters and win their votes. They argued that Biden should not be pandering to Trump supporters, who they believe are responsible for the division and violence in the country. They also argued that Biden's wearing of the Trump hat was disrespectful to the victims of the 9/11 attacks.
Ultimately, the meaning of Biden's gesture is up for interpretation. Some people will see it as a sign of unity, while others will see it as a betrayal. Only time will tell what the long-term consequences of Biden's gesture will be.
In the meantime, it is important to remember that the 9/11 attacks were a tragedy that affected all Americans, regardless of their political affiliation. We should all strive to find ways to come together and work together to make the country better.