IANAL, but in terms of the law as written, you're correct that intent doesn't matter. In terms of how the law has been applied, it does - and this matters to some degree, because the U.S. is part of the English legal tradition, rather than the French/Napoleonic (with the exception of Louisiana state law).
More specifically, if you look back over the case law for this, people generally get prosecuted if:
A) They get caught lying to the investigators
B) Had the intent to steal, whether for profit or ideology
To date, no one has been prosecuted without one of those two, or without prosecutors alleging one of those two. When I was in the military, I saw several cases where someone screwed up and put classified material on a system that wasn't rated for it, including email. Investigations were conducted, servers were purged, and those responsible got a slap on the wrist and a note in their file for committing a security violation (if you get enough of those, you lose your clearance). This is why Comey said what he did - cases like Clinton's result in administrative punishment at most, and the worst penalty was loss of clearance and thus job (which didn't apply anymore for her because she was no longer Secretary of State).
In the case of this guy, likely the Prosecutors feel they have enough evidence to allege that he was trying to sell the data, probably based on his pattern of conduct, and probably also because those selfsame tools showed up for sale on the internet.