It also bothers me that this article states quite calmly that the 1908 Siberian phenomenon was a stony asteroid, of such-and-such a size, which exploded in the air. That's possible, but unproven. It especially galls me that these people are saying how big the 1908 asteroid was. Like they know?
Furthermore, though I'm no expert, I believe that the fragile stony asteroid in Siberia caused great devastation. But, we are to believe, a solid METAL asteroid can slam into the Earth and go un-noticed.
Lastly, this line about the crater:
But this one has a raised rim, now about two metres high, but originally rather thicker.
I detect a shift in focus here. How about "I'm about two metres tall, but originally rather bad at math." This is all rubbish.