I do not think anyone here has a problem with that as long as the Cops are not dressed up and inciting anyone. Notice the AND between up and Inciting. I have been to high school football games where SGT Hayes was handing people their backsides and heard threats to him in the stands, what is wrong with people when it comes to sports?
Yes, and while SOME Raiders fans *are* disruptive and bring stuff down on themselves, so do SOME people in any victim class. The underlying point about entrapment is that if the cops portray themselves as a member of a victim group (in this case - spectators wearing other team jerseys and specifically raiders jerseys) that is in no way, shape or form "entrapment". If Raiders jerseys DO incite fans to commit assault, then I personally WANT the cops dressed in Raiders jerseys, because they are more likely to catch criminals in the act. That's a good thing.
Assume that at a venue, black guys were being assaulted by racist spectators. Would it be entrapment to have black UC's go to the game? Of course not. Would it be "inciting"? Well, based on the layman's definition of inciting, it would be, but it is certainly legal. You can do this experiment at any venue, where any particular group(s) tend to be victims of assault, etc. - use UC cops that appear to be members of that group - Raiders jersey wearers, black dudes, or whatever. If somebody *is* "incited" by a Raiders jersey, that's THEIR problem, and if a cop dresses as a Raiders fan and gets assaulted, it was neither entrapment nor "incitement" as a legal matter, although again it might be "incitement" from a layman's perspective.
From a legal standpoint, there are two ways that "incitement" becomes criminal
1) fighting words. Look it up. Pretty simple concept. People can be , whether it's constitutional or not, arrested for breaching the peace etc. IF they used fighting words.
2) Incitement as relates to Brandenburg v. Ohio. This case established (it is no longer the falsely shouting fire doctrine, which was schenck, which was used to prosecute a war protester and which was superseded by brandenburg) the limits of speech, where it becomes criminal through incitement to violent action. Note that mere advocacy of violence, even, is not enough to trigger a violation under Brandenburg v. Ohio. In that case, a conviction of Ku Klux Klan members was overturned and a rather strict standard (stricter than SChenck) was established. Look up "Brandenburg" standard for more info. But it's a pretty high bar, in brief.
As for entrapment, again, that's gotta be conduct that would cause a law abiding person, a person NOT disposed to commit crime, to commit the crime. Leaving a vehicle with engine running and keys in the ignition, not entrapment, asking a person if they would see you drugs, not entrapment, etc.
Posing an undercover cop as a passed out drunk businessman with a shiny rolex on his wrist - not entrapment
Posing an undercover cop as a prostitute, by dressing her in scanty neglige etc. not entrapment
Posing as a muslim extremist looking to buy a bomb, not entrapment etc. unless the behavior was so extreme that a person not disposed to bomb making and selling etc. would be convinced to do so (FBI has fought some claims in this regards about some of their UC operations)
Leaving a laptop computer on a car seat of an unlocked vehicle at night in a high crime area - not entrapment