NOT a safe thing to do. Cute? Yes. Cuddly? Yes. But you def shouldn't do that. Like others have said this is a dominance thing - the dog doesn't seem to show aggression but it's still trying to be alpha over the baby (new member to the family "pack").
Also, what if the dog saw a squirrel or something behind the owners and rushed to it, trampling the baby? Sounds silly but things like this are totally possible. Mistakes/accidents are always a second away.