He was a law clerk for United States Supreme Court Justice Sam Alito. Presently, he is an attorney with the Lanier Law Firm, which has offices in L.A., Houston, Palo Alto, and N.Y. I don't see a connection to Florida or the Florida Supreme Court.
On the docket, in the box under "Filed By", an attorney's name appears followed by his or her bar number. Sometimes it will read "Jane Doe" BY: Joe Blow" where Joe Blow is the attorney, and Jane Doe is (usually) a paralegal, legal secretary, or clerk for Joe Blow. Joe issues the pleading, and Jane brings it to the courthouse and files it with the clerk's office.
Misty's FLSC docket reads: "Jack White BY: Jack White". Jack filled out the petition form, wrote a letter to go along with it, and brought it to the courthouse. There is no bar number behind Jack's name. He might or might not be an attorney. Regardless, he is not a member of the Florida bar.
It should also be noted that one need not be an attorney to file a writ of habeas corpus or any other petition or court pleading. As Americans, we all have the right to be our own legal counsel.
Anyway, I looked at the docket again, and I don't see where the writ was filed again after the "Notice of Voluntary Dismissal" on October 15th. It seems he wrote a follow-up letter, probably an explanation for the withdrawal, and attached it to a copy of the original writ.
This looks like a non-issue, though I can't be certain.