Well, it dosnt really matter what answer you get as to why it was instantly frozen in the flood, simply because no mammoth has ever been found that had been instantly frozen!
The idea that there are instantly frozen mammoths originated in (iirc) the 1920 when russian scientist found one particular frozen mammoth with half digested food in its mouth. The problem is:
- the mammoth was in full decay and had been for some time prior to freezing. this was clear since the ground around the mammoth stunk from the rotten flesh. eg. its internal organs was dissolved.
- The mammoth had died because it fell into a ditch and broke a lot of bones and drowned. It showed clear signs of drowning, eg. it had an erection which higher mamals get when drowning.
- The idea that it had been instantly frozen arose by poor newspaper reporting. Even though the rotten mammoth stunk so bad (this is VERY well described by the poor fellows who dug it out, you can find plenty of original material written by guys who actually did the digging on the net) and was in a poor shape, some of the muscle tissue looked surprisingly good, and when they did the autopsy they threw the meat they cut of away to some dogs who ate it. A poor fellow even tried to cut out a piece of (muscle) tissue from the mammoth, fry it, fill it with spices and eat it; he threw up. However, that the mammoth was in so good shape that it could be eaten was created in a newspaper, and has existed ever since thanks to creationists.
So dont ask why an instantly froozen mammoth indicate the flood, because no such thing has ever been found! ask what his sources are, and show him that the WT is just a tool for propegating creationist lies when it comes to evolution.
sorry for the rant. that book annoys me!