Going out of bounds

[Clark Kent]

BJV game Team A runs a play where A1 takes the ball down the sideline, drawing defenders and then as his momentum is carrying him over the end line, but before his feet touch out of bound, he flings the ball across the court to a teammate set up for potentially an open look. Similar to a skip pass over the defense, but this pass is quicker and doesn't take as long thus potentially allowing the shooter a better look. The problem is that after A1 releases the ball his momentum carries him out of bounds where he runs along the baseline behind lead and back onto the court.

Is this legal? I know the rule states that no player shall leave the floor for any unauthorized reason. Does this fall into that category?