Please cite where Lattimore has ever run an officially timed 10.5 100m. (somebody blogging that some coach timed him down-wind in a hurricane doesn't count) The 10.70 Young ran was in a semi of the State Championships. (his 10.76 was good for 2nd in the finals) That 10.70 would have won the state title 8 times (8!) since 2000.
Let me give you an education on 40 times across different settings. At the US Army 2010 combine Young finished in the top 10 of all players in the 40...with a 4.72. WTF you say? Yep. The fastest time run by anybody was a 4.55, by Damiere Byrd. That name ring a bell? It should, seeing as how he made the Team USA Jr team that competed in Japan in the 100m and in 2010 ran a top 10 time in the nation with an official 10.42. That 4.55 is Byrd's time on his Rivals profile but, lo and behold, his Scout profile lists 4.27.
Get rid of your 40 fascination and look at times that are taken under conditions that transfer from one place to another...officially timed track times. If you gotta whine about Young's height and weight be my guest but can we PLEASE put the speed question to rest?