You can't talk someone to death, but if you live in Hong Kong and you sell the wrong books, one day you will disappear, you will end up in a kangaroo court, and nobody will see you again. So it's super easy to sympathize with anyone who is frustrated out loud, or at the very least it should not be very difficult to understand. Again, these are people with no power at all. They are maximally vulnerable. The only thing they have is a voice.
In the HK bookseller case, the people involved deliberately wrote books to dig into the personal life of Xi Jinping and discuss his alleged extramarital affairs. They were warned several times not to do this beforehand.
Is it right to kidnap these people? Of course not. But they sure as hell tried to kick the hornet's nest. I'd be more sympathetic if the book was about promoting HK democracy, but all they really wanted was to embarass the top leader.
Now, with regards to free speech. I'd like to note that the HK protesters are often a bunch of hypocrites. They start out with legitimate grievances but their behaviour resemble the type of authoritarianism protested against. They routinely sacked malls and subway stations due to their cooperation with police (whom they spend every moment to provoke and demonize). They also vandalized businesses that are perceived opponents of their movements. For example, this article (which reports one of many violent riots in HK) wrote:
Masked activists had also trashed restaurants run by Maxim’s, a catering firm that has become a frequent target because its owner’s daughter has criticised the pro-democracy movement.
If the HK government were the ones sacking stores of their political opponents, then that'd be consistent of the desired narrative of HK being run by a totalitarian government. But in this twisted reality, the pro-Democracy movement is the one perpetuating the political-motivated assaults on individuals and businesses. And instead of denouncing these actions, supporters of the movement rationalized and normalized these acts. And aside from politically-motivated violence, there's also the rampant misinformation campaigns being run to advertise how they got attacked by the police while downplaying all the damage and terror they've caused the city and others.
In any case, I love Hong Kong and hate Winnie the Pooh but I just can't find it in me to support this so-called "free-HK" movement. The movement has demonstrated not an ounce of truthiness, justice, or democratic value. People in the anglosphere only care about it because they are a great tool against CCP.