Pod2g, by his own admission, isn't a jailbreak dev. He simply (understatement!) finds exploits in iOS that can then be used for jailbreaks. Pod2g tweeted that he was no longer associated with the Chronic Dev team for undisclosed reasons and that he gave all the necessary information regarding the SHAtter exploit to both the iPhone-Dev team and the Chronic-Dev team.
It is my understanding that this is more of a group effort by the Chronic Dev team and a few members of the iPhone Dev team (MuscleNerd, Saurik, etc.).
If the new exploit truly is a bootrom exploit, then there is no need to wait for iOS 4.2 because the same exploit will be able to jailbreak it as well. All that the devs would need to do for iOS 4.2 (or any iOS after that that uses the current devices) would be to clean it up/tweak it for the new update. Look at how the Dev Team is constantly updating redns0w after each new iOS update is released. It will essentially be the exact same concept, just usable on much newer devices.