^^^The gang had plot shield. And Arthur is... Arthur. He can defeat entire armies alone obviously. But real talk, Bronte has about 50 men from what we understand. They may not be the best skilled, but having 50 armed men against you sure is scary.
Jack was also safe because Bronte practically owns the city and no cop is insane enough to harm someone who Bronte cares about.
The O'Driscoll's have way more than 50 men Comb just grabs as many men as he can do you not remember the opening missons the Camp before the train was packed plus even after Comb is dead they still had like 20 to 30 dudes at that camp in the Grizzlies and The O'Driscoll's were just as good as Dutch and his gang that's why they were still around only the toughest or the smartest gangs survived
^ No they not good fighters. By lore they were just a bunch of lowlifes that had rusty old guns as Colm didn't give a damn about them. And they obviously had no morals whatsoever. But by lore we learn that Bronte's men are extremely scary and that no one dares to touch them, not even the law. But the law don't give a damn about the O'Driscolls as you can encounter law enforcers arresting Colm's boys from time to time.
Don't think about the gameplay itself as all enemies are the same in that regards.
The O'Driscoll's were smart enough to find you at Shady Belle also if Dutch ,Arthur and Sadie didn't Intervene they had a plan to rescue Comb from being executed and they also said they had dealt with worse so obviously Saints Dennis cops aren't that good they just have a lot of them and brontes men really aren't that good ether like you said 50 men is 50 men but what that doesn't apply to the O'Driscoll's like wtf nice logic and when was it a trait they had rusty guns like I understand some of them have worn down revolvers but not all of them had old weapons it was a mixture and the easily could of killed bronte
And the reason why Bronte's men won't get a arrested Has nothing to do with how good they are or how scary they are it has everything to do with how Bronte has used his money to gain power with in the city do you not know how organized crime works
^ Bronte owned the police department and all it's manpower. He could've easily sent down the entire Saint Denis law on Colm if he desired, so no need to use his own elite guards to fight Colm.
Also, the fact that Colm DID get caught proves just how weak his gang is by no being able to protect him. Yes they had a plan t rescue him, but it's obvious they would get caught immediately and killed on the spot. As just a couple of cops (and yes, sniper Arthur) managed to fend themselves against a full wagon of backup O'Driscolls.
But let's not go off topic. Jack was safer with Bronte as there's no reason for Colm to fight Bronte as they're already fighting Dutch (and are losing).
At the very least, Dutch should've waited until he defeats Colm and finds a safe spot for the gang before he took Jack back.
Yeah but there's even much more to deal with in his life.
Spoiler:
Like Edgar Ross killed his dad... John Marston and Edgar Ross gets what he deserves from Jack Marston.
It's A Hard Life...
Them still being alive as a gang at this point in time still proves how strong of a gang they were Comb could've gotten captured in a multitude of ways hell The pinkertons could've caught him could've been a job gone wrong and all the O'Driscoll's you find captured in sheriff wagon's always being halfway rescued until Arthur shows up and kills them just proves that Comb has so many men and if Arthur doesn't take out everyone they would've rescued Comb and in your theory world if Jack isn't reunited with the gang it's most likely because the gang is dead I don't see any other reason why they would leave Jack and when comb is saved they ether leave or stay and have some sort of problem with Bronte which would lead to Comb sneak attacking him the same way because he's not stupid he made the plan to kidnap Arthur and Dutch had no clue what happened till Arthur got away Comb would realize the cops are on Bronte's side and he would need to take him out if he wants any money from Saint Dennis
^ Because he could've just locked Jack in some basement to save some money. But he went on his way to clear a big room in his own mansion, fill it with toys, books and give it all away for Jack. He feed Jack with food from his own kitchen. He taught (at least tried) Jack Italian.
It shows he cared and liked Jack. And clearly has a big heart for homeless children, considering he takes even low life urchins under his wing.
And we don't see Bronte having kids of his own, maybe he planned to even adopt Jack?
Overall it's obvious that if the gang never showed up he would still keep Jack since he already knew about the fact that the dead Braithwaiths can't pay him for keeping Jack but he still kept him.