I'd say good luck to anyone pushing that argument. Again, that the FSA has not chosen to regulate bitcoin as yet, and the fact that there are no regulations specific to bitcoin do not mean that these businesses are not subject to applicable laws. It's a matter of which regulations bitcoin falls under, and when the FSA or other appropriate agency decides to pursue that matter.
I get what you're saying -- fraud is still illegal. But securities laws are very specific. Insider trading laws are much more limited in the commodities markets (I was regulated by the CFTC, so I know a little about this). Insider trading laws don't exist with Bitcoin.
Outright theft is illegal, of course. Front-running? I don't see how that would be considered illegal but could certainly be grounds for a Civil case.
See what the FSA has to say about it. And then ponder how the law could conceivably be interpreted. I can't be bothered, personally.