She cannot be involved in politics
Royals are never to express their political views. They don’t even vote in their elections. When Diana got involved in the cause of eradicating landmines in the last year of her life, she was chastised by the British government as a “loose cannon” and a “political figure.” Her response: “I’m a humanitarian figure.”
These days William, Kate, Harry, and now Meghan are following in Diana’s footsteps by embracing causes that were off-limits a few years ago, such as mental health and women’s rights. It’s clear the monarchy knows it has to modernize itself in order to stay relevant but will still stop short of endorsing specific candidates.