Lyme by itself probably would not cause death from what I have read but some of the other tick-borne infections can. I believe Rocky Mountain Spotted Fever can cause death. Hopefully the autopsy will show the cause.
Certainly such a chain of events would be rare for Lyme/TBI, but that's about all I can say.
Another source that may have more ideas/information for you would be the National Lyme Disease Memorial Park Project. It is run by volunteer advocates, many of whom are Lyme patients. They have been keeping track of Lyme and TBI related fatalities. Their website has contact info, they may be able to help you?
http://www.lymememorial.org/index.htm
A tick bite is just like any other insect bite...compare to a mosquito. Not all ticks carry Lyme. Just as not all mosquitoes carry West Nile.
I am not sure what happened with that young man. Have never heard of Lyme working like that, but there are others on this list who know more than me.
As far as bites go..... I can't count how many times I have been bitten or infested with a tick or too. When I say infested, I mean the tick has attached and the head is already under the skin and sucking the blood.
Not much you can do to avoid ticks if you are going to be active outdoors except take common sense precautions.