Yes, it was probably a comet, although the difference between a comet and an asteroid is getting murky the more we know about these things. Whatever it was exploded high in the atmosphere above Siberia but the flash was seen in London so bright you could read a newspaper at midnight. As to the rest of the author’s conjectures, they are his and he is welcome to them.
Did you ever read the book “The Fire Came By” about the incident in Siberia?
I’ve had it for years....guess it is time to re-read it.
The authors were John Baxter and Thomas Atkins....just went and pulled it off the shelf!