He didn't have the right not to make a decision. As a responsible citizen he had the obligation take action and decide how to approach the issue, and he did the best he could as a single individual. Deciding who to trust is doable; filtering all the information on those docs by himself is not.

Yes, he could have disclosed the obvious things, but how would that work out on the long term? Would he be able to address by himself all the questions that would follow up? How much information would he be able to disclose? Too much information and he'd risk disclosing legitimate operations, too little information and he'd soon get discredited.

In the long term, it would have meant that people like me who think there is a legitimate reason for nation states to have intelligence agencies could support him with clear consciences.

He did not disclose all the documents. He made a pass through first to protect people primarily. The vast majority of what he passed on were power points and lists of devices.