No that's not what being an anti-hero is. Though an anti-hero might very well do something like that. And often they might change their minds last second or something and normally only in a few rare cases. Say the kid reminds them of themselves or a family member, etc.
This is the definition of an antihero on wikipedia.
In fiction, an anti-hero is a protagonist whose character and goals are antithetical to classical heroism.
And someone called this bullshit logic, and everyone is going to have their own idea and definition of what an anti-hero is. Though it sometimes all becomes meaningless since a lot of this shit is really subjective even if they don't want to admit it.
There's little difference between Heroes and Villains in these stories in reality. So we have to either pick a definition we agree on and go from there or we're going to be arguing with unmatched words.