The author's an idiot. The 'reasonably believe' standard is subject to review and is measured against a reasonable man standard. Individuals aren't protected by Stand Your Ground merely by telling themselves they 'reasonably' believe they are responding to a potentially lethal threat.
And the author may never have read the law, because the law also applied in the case of a threat of 'great bodily harm' not just a potential lethal threat. Those who write editorials should start first by reading and understanding the subject matter about which they write.
Well, at least if they want to tell the truth. This guy's a lib so all that would be extraneous effort.