This seems like less of a "knot" which we're supposed to avoid with amsteel than the OP's version. With a long enough bury, I wouldn't think the stitch is necessary either. The buried tag end is easily seen in amsteel and a mark can be placed indicating the location if anyone is worried about slippage. Seeing the OP's style of bury makes me wonder why a soft shackle "button" is an acceptable practice and why this OP's may not be. I like the idea of a locked fixed loop without stitching.
The stitching is to keep the tail buried with low, or no load, even flexing the splice at this point could cause part of it to pop out, especially the slick dyneema. The stitches don‘t help with break strength much.
I highest I seen for a dyneema knot that didn’t slip was 50% of the cords break strength. The rate of pull also has a lot to do with when the rope will break, the faster the pull the sooner the break because of the friction generated heat.