Easy way to fix this.
Completely shun any season ticket holder who allows their tickets to end up it the hands of select opposing teams fans. I can almost understand the Cowboys since they suck now and since they are close and they are NOT a division rival anymore fine, go ahead although to me that's pure sacrilege. Right now I'd have the following list.
No 49ers, no Seahawks, No Rams, No Steelers and No Packers fans... The Packers have recently beat us in a playoff game and are NFC dominance rivals. I'd even say New England but that's just me, that one probably would not stick but that's at least a good start so it's not like saying Bengals fans would be a problem or a host of teams that would be a problem just a select few.
KC does this, YOU as the season ticket holder ARE held responsible by ALL the fans who sit within a few rows of you of who you let sit in your seats.
They would be ok for instance with selling your tickets to say Cardinal fans or something like that, some team they do not have a huge rivalry with. So it would be a minor offense if you sold them for something like that.
However there are teams that would be no go's. Mostly any team from the AFC that is dominant or any team that had ever beaten the team in an important game recently or if in the playoffs forever.
Thus in KC never sell your tickets to in order a RADIERS fan, Broncos fan, Steelers fan, Colts fan, Chargers fan, Bills fan or an New England fan. ANY of these things is like a capital season ticket holder crime and it WILL NOT MATTER if you yourself did not sell them to those particular fans, YOU will suffer the wrath.
They know who you are, they know who your family is and if you sell your tickets and some God forsaken Steeler fan or Bronco fan or Raider fan is ever in that seat YOU will be shunned without mercy and pelted with unmentionable stuff for at LEAST a year if not more.
To the opposing fans themselves the are actually very nice by NFL standards. Not saying it's a good idea especially if you are a Raiders fan but you probably will live. This in any case is probably going to go better for you than if it was flipped around and a Chiefs fan was at their house.
THAT's how you stop that.