Not taking the Palace clown's effort too seriously...but the term 'plastic fan' does seem to have become pretty much a catch-all term of abuse.
Tried putting it into Twitter earlier just to see what came up, and within about a minute you could see it applied to Man Utd, Man City, Spurs...
That's got to have been done by some 20-year-old who never went to the Goldstone. A whole generation of Palace fans grew up very confused about who their rivals were, when we were only in the same division about twice in 20-plus league seasons. Some of them started looking to Millwall, Charlton...