Hey, it does sound like Gremlin would be fit for the job!
That said, our first Pit Bull Annabelle was terrified of kids. We didn't know this until a couple holiday run-ins with kids that set her off. On Thanksgiving she lunged at an older boy (maybe 10 years old) for no reason. Fortunately my husband was right there.
Then on Christmas my little cousin walked behind her and startled her, she went crazy barking at him. We had to remove her from the room. She was not socialized with kids as a pup, apparently. For this reason and her dominance aggression issue we rehomed her as we really needed a dog that was bomb-proof with kids. She was socialized well by a trainer before being re-homed and got a great home with teenage kids.
Fortunately, Satin is what we needed, even though she is a crazy lady, she is super gentle around kids. My mother-in-law's Yorkie dog on the other hand, is not going to come near my kids. I don't trust that dog. It's not good with adults, let alone kids! I could just see her nipping now.
While it doesn't sound like Riggs is going to ever be 100% fine with kids, it's good that you at least want to control it, and there was some great suggestions made here to work on it. Let us know how it goes!