An argument can be made of the OP stating the franchise is "most heavily policed team." However, the league has instituted rules following the actions of a player associated with this particular franchise. That is not debatable. What can be debated is whether any other franchise sparked a number of rule created in similar fashion exceeding the Dallas Cowboys.
I do not know. I have been watching the NFL since the early-1970's. This franchise began a decade earlier. The league is over a century old. I saw PLENTY of horse collar tackles before Roy Williams hurt several players doing so in 2004. A few of those horse collar tackles I had previously seen resulted in injuries also. Yet, it took until after the turn of the century before the NFL finally decided to say, "Whoa! Let's make that tackle illegal now because it ended up hurting players! I mean, it has hurt players in the past but it should not have hurt THESE players. I mean..."
Seriously. Other franchises have contributed to new stipulations added to the NFL rulebook. I am curious whether other organizations, some which have been around far longer than the Dallas Cowboys, have longer lists.