It does make a difference. Rather than release the exploit and have Sony patch it faster, he waits for them to find the bug themselves and patch it so there's a range of firmware versions which have it. And in that time, he can also improve the exploit to make it stable.
No it doesn't. People here are waiting mostly on 4.06 or lower, even as low as 1.76 for it, which means most them don't care about bugfix, PSN, games or updates in general. (And what serious bugs does PS4 has still after so many years besides those mysterious stability improvements?)
He just wanted to keep the hype and seek as much attention as possible. As long as nothing got released, its as good as nothing.
I bet the CIA got exploits for PS4 too, just they are wait until WikiLeaks post them first. At least CIA won't post on their twitter and call people asking such questions beggars.