You might find "brotherhood" amongst the fellow members of your club, if you choose to belong to a bike club, but this alleged extended family of "bikers" who are all fluffy and wonderful and helpful to each other, no matter what, is a complete myth in my opinion.
Yep - you'll find some remarkably fine individuals within the so-called "biking community". No doubt about it. You'll also find some of the worst representatives of our society.
I admit I'm guilty of assuming I'm less likely to have stock stolen at a bikers rally than I am at other sorts of events. It's an utterly stupid assumption, as so many assumptions are. Just because someone happens to ride a bike doesn't mean they're not going to be a thieving barsteward.
As for "what happened to agreeing to disagree"... that's more a statement I'd associate with "polite society", e.g. agreeing to disagree if a discussion gets a little heated over the dinner table. It's not a statement I'd particularly associate with "bikers" (whatever "bikers" are).
Just because there is a common factor of travelling the roads via 2-wheeled motorised transport, doesn't mean everybody's going to agree with everybody else... & I'd be bloody worried if it did!