The page he accessed probably contained thousands of Google borg jobs. Many about secret or future projects for example. Many giving implementation details for secret sauce algorithms (eg. oh - they precompute all possible misspellings for their spell corrector via this mapreduce!). Simply knowing the fleet wide CPU, network and RAM usage for Gmail would give a competitor a lot of knowledge into the probable running costs of the service for example.
In this case he exposed a tiny proportion of what he accessed.
In this case he exposed a tiny proportion of what he accessed.
Sounds fairly reasonable to me.