If there’s no forced entry, how did he get NG to open the door? Maybe he said, “Hey, it’s so-and-so, and your (son, daughter, grandson) needs help (as in, accident or ill) - please come with me- I’ve been sent to get you” for example (only) and/or he identified as someone she knew so she opened the door
Do we know for sure that the front door is how he entered? It seems plausible that in one scenario, he could come to the front door, disarm the camera so that when he's ready to leave with NG, there's no camera footage. He doesn't have to enter the house the same way.