The possibilities are endless. He agreed with the result but not the reasoning. He agreed with the reasoning but not the result. He did not think the panel opinion was sufficiently convincing to be upheld at SCOTUS. He thought the issue was sufficiently important to merit en banc rehearing regardless of the outcome of the panel decision.
Don’t take my word for it:
I think we can agree that Bricker is sufficiently conservative and/or pro-gun that his views on the issue are not politically motivated.
Well, the Judiciary Act (as amended several times) sets the number of justices at nine.
Possible, but it just kicks the can down the road. A recess appointment is only valid until the end of the next legislative session, so the Senate would still have to confirm someone in 2017.