That's a very philosophical argument, but in practice there are levels of secrecy, often in government classification. Those determine which people with what type of security clearance have access to the information.
The sentence also means "he is very secretive", which expresses that there are vague levels to how secretive an individual might be.
Actually, though I take your point, my experience is that it's not strictly true. Some secrets are closely guarded and known only to a select few, who meet particular requirements of trustworthiness. Revealing these secrets likely results in severe penalties because the information can result in great harm if known to others. These would fall into the category of top secret. Other secrets are less closely guarded and failure to protect them results in less severe penalty and less damage if they are spilled. Nonetheless, they are considered secret because the initial holder(s) of the information prefer(s) for any number of reasons that it not be widely known.
I had a few problems, I think mostly due to the difference between European French and Québébois French (I speak the Québec version), but I had very little trouble with the voice recognition. I hated the program as a stand-alone learning tool, but it wasn't the voice aspect, it was just the structure of the lessons. I need to know what I'm trying to say and why.