I’m willing to bet several things:
1) Grandma was not the alpha of the pack.
2) Grandma left the room and left the dogs alone with the baby.
3) Baby was not in his crib or otherwise out of the reach of the dogs.
4) Despite the neighbor’s anthropomorphism, the dogs were not “jealous” of the baby. Apparently those dogs did not recognize the human as being part of the pack.
“Missed One” Ping.
Dreadful. RIP.