Yes, but you only told part of the story.
It's true that the Flyers of the 70's attracted a special 'niche' of fan and their road games did mean higher attendance is a number of U.S. cities (not Canada).
When other teams visited those same cities, attendance was lower - not bad but that 'niche' of fans did not attend.
But far from being happy (I have no idea where you got that from), Campbell had a problem. It made some sense that if all the teams played like the Flyers and their brutal methods, that those niche fans would come back for the other games.
There were 3 things that brought the NHL to their senses:
1. Having such a league with Flyer clones was not sustainable - the violence would escalate, it would lessen the skill level and it would be suicide for the NHL.
2. Those 'niche' of fans were not the type of corporate or otherwise season ticket buying fans.
3. By that time, there was tremendous pressure politically and from the courts in Canada to reign in the violence.
If Campbell says anywhere that he liked how the Flyers were bringing in fans, I would really like to see it. Even Campbell realized that hockey couldn't grow that way - it was actually counterproductive.
But he sure liked the fact that they were the league's best road draw, usually selling out arenas more than any other team. The NHLs position on the Flyers was somewhat two-faced: saying all the politically-correct anti-violence statements, but not actually doing anything about it.