fwiw, weaving will not appreciably warm the tires to any greater degree than will riding in a straight line, most certainly not with only a 1km distance to get things going. if there was no other warm up generated- riding several miles, sitting in hot sun for a length of time, etc.- then those tires were functionally cold at the time of the crash.
it's been mentioned twice now, so thought it prudent to dispel that notion.
I have to say you have dispelled a myth for me. I always thought it helped. I will put that in the must remember file.