I am glad they didn’t have an ending to further traumatise Ryan. The whole point is that despite the circumstances of his birth, he’s grown up a normal, chirpy young lad thanks to Catherine, and there’s hints he’ll join the police.
Putting Ryan in a situation where he has to kill TLR, or TLR attacks him, or witnessesing TLR burning alive, would greatly traumatise Ryan and mess him up and could basically ruin his future. I don’t feel the need to see that child (he’s 16!) traumatised and suffering.