Unconnected Copper Pour or Not?
You can stitch otherwise floating island copper to the ground with short traces and vias. 

General advice is usually to avoid floating copper islands, especially near RF circuits, because of sneak coupling and other unforeseen effects. 

When doing polygon pours, we normally use the "Remove Dead Copper" option in Altium Designer. 

Sometimes commercial PCB manufacturers will request to put down floating copper to prevent "copper thieving" (to balance the electroplating). See, for example, this question. A review of the possible effects should be done before agreement is granted.