I thought by leaking it that it would encourage comex to release the jailbreak faster for everyone else.
What do you think he's doing - just sitting around and enjoying us wait nervously? He puts all his time and effort into this.
Here's the thing: exploits are very hard to find. Apple patches them soon. If you have one, you stay silent about it, until it works on all versions flawlessly, so that everyone can enjoy it.
It is too early to tell, but if this was a very early stage of testing (probably not but could be), you could very well be responsible for this jailbreak not working on a subset of devices, like the 3G iPad 2. Again, it is too early to tell, probably not the case, but whoever leaked this very well could have just screwed over thousands of users waiting for a jailbreak. And undone all the hours and effort comex put into it. Worst, he may be so pissed about the wasted effort, he may stop developing. That's why you wait for the final product.
I can't believe I have to explain that.