I've read The two Babylons.
It is an interesting premise.I am aware that he got MANY things wrong in his book. He was using the best information available to him in the mid-19th century. There has been a huge increase in knowledge since then.
I think it's unfair to throw everything he did out, He , without a doubt, jumped to many conclusions that don't hold up to current knowledge.
I wish someone would go be and reexamine his work and see if it holds water still.
Never the less, I believe, if you look at Egyptian Mythology, it rather supports the idea the Shem either killed, or had him killed. Osiris seems to fit Nimrod's description well, and Set seems to match well with Shem. Set is often described in bad ways, which would make sense if you were a worshiper of Osiris.
I don't hold to that as absolute though, and if I'm wrong, no big whoop.