The average time before bitcoin-denominated stock fails or is shown proven to be a scam is ~ 1/2 a year.
This lends itself to, as you say, "playing games," but becomes a headache with government regulations in place.
If the new law allows companies to advertise stock to the public whilst being risky then I see no issue. I imagine the system will be in a similar vein to Kickstarter, where instead of just backing the company with donations you can invest instead.
Because this is open to the consumer it is up to the consumer to do due diligence.
Kickstarters fail all the time, everyone knows the risk they take when they lay down cash.
If the new law allows companies to be formed in that fashion, I see no issues with failed stock. Companies do fail all the time, in fact that vast majority of businesses will not survive past a year, its not just unique to Bitcoin.
The exchange will have to tell the user the vast majority of companies fail, and thats just plain nature, no other way about it.