Rather then actually fix the problem (say by requiring a 5 minute minimum time for placed orders) they simply make money on the traders and then when the market goes down find a scapegoat to arrest for doing what their system explicitly allowed.
A
two second minimum life-span for orders on all exchanges would be the simplest and most effective action regulators could take to stabilize markets. That UK trader should get a medal for highlighting how broken the HFT-abused markets are.
Personally, I think that if you publish an API and someone uses that API they should by definition not be doing anything illegal (within the context of that system). Your API should not allow illegality.
Now let's split hairs; if a hacker pushes executable code through a bug in your API its not illegal yet. But that executable code then runs on the server and probably does something illegal (opens a backdoor that wasn't part of the API, transfers $, etc). Similarly, if a hacker steals your password, logs in and steals your bitcoin, his use of the system wasn't illegal but stealing your password and subsequent use of your $ sure is...
You can call me an engineer but actually I think that the perspective above is what Bitcoin tries to do and one of the reasons why it is so appealing... the above is essentially an emergent property of a zero trust protocol.