I think now I can understand why Beijing is so adamant on the extradition and now the security law. With Hong Kong having its own governance and no extradition law, its 's pretty much a save haven for foreign actors that can blend in under the guise of "democracy".
Looking at how the protests progress to the point of demand for Hong Kong's independence, it's ridiculous to expect Beijing to back down and do nothing in the end.
That would be like if in the cold war Guam/ Puerto Rico as a US territory become a place where KGB agents can go and collect intel with impunity from US laws from because coveniently the government there has it's own laws that's different from US laws and there's no extradition law so they can't be extradited and tried under US laws. Furthermore, the government there is a symphatizer to the communist cause, so they won't out the agents willingly.
And then when the US move to cover that loophole the Guam/Puerto Rico goverment and a part of the population decided to protest and tell the whole world that living in the US is bad and they want independence, even inviting the Soviet Russia to occupy the territory.
The stupid question would be: will the US government back down and let Guam/Puerto Rico go?
I had a response to your previous post, but it was lost.
The protesters originally formed in March/April in response to an extradition bill that was meant to send a murder suspect to Taiwan. Since Taiwan is technically "Mainland China" under the law, HK could not sign an extradition agreement with their authorities.
The Chief Executive (equivalent to Governor) had originally proposed this bill because people were upset that a potential murder suspect could be released without punishment.
At some point, the narrative completely flipped on her and the protests began. To be fair, this is not completely out of the blue. The lack of extradition between PRC and HK was because HK people were initially fearful of being prosecuted for political crimes in the mainland.
Compared to Guam and Puerto Rico, the national protection is even weaker. In those places FBI and NSA have federal jurisdiction. In HK, there is no jurisdiction at all. There are espionage laws that HK police could technically enforce, however, they are trained mostly to deal with street and organized crime, not state-level actors.
I wouldn't even say the HK government is sympathetic to adversaries is an issue (I don't think it is). The issue is that catching spies is extremely difficult. Say there is a "businessman" in HK who is crossing the border to meet his contacts in mainland China. To HK authorities, this guy looks like any other businessman doing business in China. If you had an FBI, you'd be able to track his movements across state lines. However, in China's case, there is no uniform way for them to keep track of what happens in HK.