Salty? That would be the people still bitter at Manly for the events of 20+ years ago.
Cronulla haven’t officially taken over anything, the St George comp has just withered on the vine to the point where their teams sometimes need to play in Cronulla’s comp to survive, just like Norths’ junior teams have played in Manly’s comps on and off since they were booted. That’s not a positive, it’s just another example of a suboptimal arrangement in RL. Look at it from an outsider’s perspective- does it make sense to have St George cover the St George area, have a big gap in the shire, then cover the Illawarra? No, it doesn’t. Does it make sense for a dead NRL team to cover the North Shore? No, it doesn’t.
I don’t know why you think the Bears will happily give up the North Shore after a move to WA. If the NRL give them their list of demands, it will legitimise them hanging on to it (and hang on for dear life, they will), leaving the north of Sydney trapped in a suboptimal arrangement. You’ll have the Bears feeding into WA, with a weak presence on the North Shore, and Manly on the Northern Beaches. That’s not having the area live up to its potential.