That image - it comes up on the post upthread but not in the quoted version - is a red nosed pitbull. It's to be wondered whether they might be viewed as the dangerous animals they are were they given their correct name of pitbull cross. There is no such breed as an 'XL bully' - these are mutations and hideous ones at that.
I've no idea who could feel an affection for these liabilities, unless your dog of choice happens to be Cerberus. They're a danger to humans - adults as well as children - and other animals. No one can anticipate what might provoke an attack, but rapid movements are one possibility and children do move rapidly. Check the list of owners who have been killed by these canine terminators: some of them were known to have been experiencing seizures.
Given the prolific reports of these incidents, anyone who wants one of these things around their home, much less around children, is an idiot. The anthropomorphic variety of dog-owner who insist their mutt is a 'softie' always think they'll somehow be different, that the reactivity and volatility bred into these dogs' very DNA will somehow elude them, and that of course 'it won't happen to me'.
Until it does.