Gary McKinnon was not "looking at 70 years". If you are charged with 7 counts of the same offense, each carrying a possible 10 year sentence on the outside, you are absent other circumstances "looking at" 10 years. Like offenses often "group" under sentencing guidelines.† Under grouping rules, the damages for each charge might be summed to produce a single sentence.
But the 10 year claim is also suspect. These are federal CFAA charges. They have a base level for first-time offenders of 6 (0-6 months). The damage claims for each charge in the indictment were "more than $5,000", the lowest damage accelerator, which adds 2 points. (If all the charges were grouped for sentencing and the damages summed, they'd instead add 6 points) The fact that his targets were military adds another two; he's now somewhere between 10-14.
For a first-time offender, that's a possible probation-eligible sentence of 6-12 months, and no longer than 15-21 months, if his lawyers were able to do nothing else to secure leniency.
70 years is horseshit.
† Here's a slide deck on the grouping guidelines: http://www.ussc.gov/Education_and_Training/Annual_National_T...