The after effects of epinephrine (aka adrenaline) are interesting - while it’s still in the system and no longer needed, once it’s out of your system and you’ve got no blood sugar left, and (as might happen to GZ after a year of fear over this kangaroo court) after a large number of epinephrine events (PTSD).
While it’s still in your system, you can seem jumpy because you react far too quickly to little things, or you can seem unnaturally calm because you have a lot of subjective time to process what is being said/done before it’s time to respond, so that your reactions all seem extremely rational and smooth.
As for once the epinephrine clears your system, it’s a lot like an athlete an hour after a marathon or championship game. You don’t seem like you want to do anything or react to anything - apparent calm.
And in the long run? Zimmerman will probably get meaningful death threats for a long time, and multiple threatening actions that may be real or just intended to intimidate/provoke. If he avoids PTSD, it will be a miracle.
He won’t escape it. If he survives 5 years, I’d be surprised.