If you want a proper Walmart analogy then you should stick the child in a remote part of a vast parking lot, so that there's no reason to expect the staff to notice.
A more accurate analogy would be if they ushered the child into a backroom where a stranger was seated across from them with a glass divider between them and then they left the room. This is the whole point of Omeagle, to facilitate these interactions. Would it unsettle anyone if Walmart were doing that, and would they be legally responsible for whatever happens in there?
If you want a proper Walmart analogy then you should stick the child in a remote part of a vast parking lot, so that there's no reason to expect the staff to notice.
And at that point the case seems too weak to try.