I really don't see how Cracker saying that to Luffy has any relevance? Most of the Yonkou and their crew members can't really be described as being unbiased nor seem to care much about bounties. For them everyone is pretty much trash below their feet and why bother differentiating trash? Heck it's highly questionable someone like Cracker even knows all their bounties.Problem is if kid really broke his armor n left a scar like that on Cracker than the words like" i can't believe a scrub like u will break my armor"(Cracker to Luffy) makes no sense at all.
As both kid n luffy comes from same generation with almost same lvl of bounty.
Even if kid don't want to continue the fight then also it would turn into a full fledged fight as Cracker can make an army of those biscuits soldier n send it towards him.
Also the way he said very few guys have seen him also suggest that only family members have seen him.
And he might have got the scar when he was a kid(as we saw most of the BMs kids are like psycho) which he later incorporated in his armor to make it look realistic.
I never saw that Snack panel. Thanks for posting it.