Is a jockey pole (a pole that exerts outward pressure on the line that controls the fore and aft position of a spinnaker pole) an outrigger?
No. When a spinnaker pole is set, the line that controls the fore and aft position of that pole is a guy, not a sheet. A jockey pole putting outward pressure on a guy is therefore not an outrigger, defined by rule 50.3
(a) as a "fitting or device" that exerts "outward pressure on a sheet or sail".