I agree that he is overstating the mens rea requirement for second degree murder.*** However, second degree murder requires more than just recklessness. The prosecutor would have to show that Zimmerman's behavior was "imminently dangerous to another and evincing a depraved mind regardless of human life."
The depraved mind requirement requires, for practical purposes, that the likelihood of someone dying as a result of the action in question be both very high and obvious to any normal person. Which of Zimmerman's actions meet that standard? There's a fairly strong argument that it was negligent, or even reckless, for Zimmerman to exit his vehicle and follow Martin on foot. But I don't think it can be concluded that the probability of an innocent person being killed was so great and so obvious that the act of getting out of the vehicle was so "imminently dangerous" that it "evinc[es] a depraved mind" indifferent to human life.
Hindsight is 20-20, but I would say that Martin's death, while not completely unforeseeable, was not nearly so likely that the act of getting out of the car and following demonstrate depraved indifference to human life. I don't think Zimmerman intended or expected to shoot Martin, in self defense or otherwise, as a result of following him. And I don't think one can say that any reasonable person without intent to kill would think that following a person in that situation would be highly likely to result in shooting that person. Unless there is something more, I don't even think that's a close call. Do you disagree?
***EDIT: I misunderstood AlBell's post; he did not overstate the mens rea for second degree murder. He was saying that second degree might be charged if the prosecutor had reason to believe that Zimmerman shot Martin with premeditation, but did not think she could prove the premeditation beyond a reasonable doubt. That would make sense. I'm adding this update rather than changing the post because there seems to be a dispute over this that is on the verge of becoming personal. So for the record, I found AlBell's post confusing, though now that I see what he is saying I agree.