I think what you have is the classic example of a “late bloomer”. I don’t weight training in and of itself mattered as much as his applying high intensity training at a time when his hormone production was at its highest point in his life to go along with a growth spurt. If he had well rounded motor abilities and was running 11.7ish as someone who was not near the end of physical maturity then entirely plausible and not out of the question. However, if he was already physically mature then it’s entirely suspect.
I got interested in this and looked into it, according to himself and other people around him, he was not a late bloomer. He said before this he didnt give as much specific attention to his legs and wasnt dedicated daily to weights. He didnt grow a lot from grade 10 to 11 when he made his huge speed gains.
Also takes purple K creatine if it makes a difference.
Now I should mention drug rumours about him and all, but talked to some guy who ran on his relay team and he was 5’8 in grade 10 and 5’11 in grade 12, and steroids fully stunt your growth, correct? Therefore a 3 inch increase in height should negate any drug rumours.