They certainly do have a right to their beliefs. I would like them better if they had a narrow focus of U.S. Police overstepping their bounds, and the mistreatment of black people in the U.S. I agree completely that that's a problem.
But they've expanded their agenda beyond that, and muddled their goals.
I think the challenge is many people have campaigned for improved civil rights and police reforms under the 'BLM' banner without knowing who the core organization actually is.
In the UK you will be banned from football stadiums for performing a 'white power' clenched fist in the crowd, but the BLM Marxist black power clenched fist is performed before each match by kneeling professional players in memory of the death of George Floyd several thousand miles away and many months ago last year.
This confusion about racism and efforts to signal support are IMO very clumsy, comingling Marxist politics with laudable efforts to support unfair and heavy handed policing of some black people.
Similarly the comingling of a minority of 'far right' wingnuts amongst moderate conservatives, greatly amplified and distorted by the corporate media, has gravely misrepresented mainstream common sense concerns.
The various sensationalist media companies have a lot to answer for, they are fanning the flames of division, encouraging bigots and ignoring the mainstream masses
But they've expanded their agenda beyond that, and muddled their goals.