Obama was 47 in 2008. According to an actuarial life table from the SSA, the odds of the average 47 year old man dying before his next birthday is was 0.248%. It rises to 0.348% by his 51st birthday. McCain was 72 in 2008. The odds of the average 72 year old dying is 1.96%, and rises to 2.64% by the time he's 75. That's a significant jump. Even with the best medical care, in your 70s, there's a chance of even seemingly healthy men dying from heartattack or stroke. I don't think there was anything close to that high of a chance of Obama being assassinated, solely because of his race.