What you are describing is an entirely different kind of misconduct than “insider trading”.
Such activities would be criminal regardless of insider trading. What difference could it possibly make if insider trading was legal?
Should we maybe add more laws to forbid such activity in different creative ways, so instead of being doubly illegal it would be triply illegal?
Crazy.
Killing your neighbors with a gun is illegal in both France and US? Here in France, one cannot purchase a gun. Guess what happens when you make gun sale as easy as possible?
Oh but people can own gun, they just should not use them illegally! Right?
K-mart could stop marking everything "on sale" 100% of the time and make the regular price the discounted price, so people don't feel like they're getting a good deal. Then their sales collapse and they go out of business, because consumers are robots with predictable emotions.
Or the board could look for the absolute worst CEO they can find, thinking to themselves "This guy will surely bankrupt the company if we give him control", and then have all the written documentation being reasons why he's a great CEO and put out press releases bragging about him.
If you look at executives loading up on put options and say "surely that proves intent", then they'll instead call up their old Harvard buddies at Goldman Sachs and tell them all the reasons the new CEO's going to be great. They'll take the hint and load up on puts on his behalf, then 10 years later give him a cushy job at the hedge fund.
Maybe they wouldn't do it to a successful company. But if a company starts declining, has a couple bad quarters... the executives start looking for an "exit strategy", and you just legalized a whole class of them if they accelerate the decline as long as it's too hard to prove intent.
If you try to ban specific examples and legalize the general principle, they'll spend years of their life arranging for companies to be bankrupted in ways that are hard to prove illegal. There'll be documented "good reasons" for everything, but despite that they will be millionaires and their companies failures.
You can't look at the most obvious case and say "we'll just ban that". It's not how these people work - they are reading the law and planning around the edge cases.
There is a global feed of press releases that companies release into, and the average HN commenter is incapable of distinguishing frauds from real better than anyone else. The executives that make these press releases use different language that doesn't describe it as fraudulent, and this makes it non-obvious.
If the "trading profit" is the only signal you have, I'm sure Goldman Sachs can come up with a way to make it less obvious than "buy lots of short-term expiring put options on your own company". You can't look at only the obvious case - you have to look at all possible things all finance people can do and rule out any possibility of profiting from a downwards movement that was engineered. Otherwise, they will profit from the gaps in your ability to detect them.
In order for something to be a crime, it has to be proven "beyond reasonable doubt". Say with 90% certainty. That is, 2 bits of certainty. But you can make a trading profit while leaking 1, 0.5, or 0.1 bits of certainty. It is extremely difficult for non-specialists to detect a trade pattern based on a leak of 0.1 bits of certainty.
Like you could buy put options to set up a leveraged short position, take all the company's money, set it on fire in public(or make a stupid acquisition so you can't easily be sued by other shareholders), watch the stock price drop in a predictable manner, and profit from the predictable decrease in equity.
Sort of like how you can't buy life insurance and then immediately commit suicide and still get paid out.