Coincidentally had child porn on his machine.
There's still the court-of-public-opinion element. Such a charge might give allies / witnesses for the defence pause to come forward.
Facing multiple independent counts also increases pressure, costs, and distracts attention for the defendant against any one case. Given the defendant here is representing himself, that may be a major hurdle. (Last sentence here is a stealth edit FYI.)
Whether the CP charges are justified or strategic I really can't say. The practice of digging up additional dirt on defendants in specific instances is a venerable tradition however.
A smart leaker would then delete them and destroy any disk they touched.
Even if they knew he leaked them, there's no guarantee he would have them on his machine. Which would be another reason to ‘sprinkle some crack on em,' that way he would still be punished if he was prepared.
And the prosecutors will put them back. Just like police inserts a small package in your backpocket when they arrest you.
Apparently the "vault 7" leak was centered around how devices were hacked to spy on private citizens and consumers. The public has a soft spot for people who leak things that expose direct invasions of privacy. Chelsea Manning on the other hand leaked documents that I don't believe would influence public opinion of them very easily (diplomatic cables and different military things).
If you were going to break the law (planting evidence) to smear the character of someone, smear the person who has a higher chance of the public siding with.
I still agree they could have smeared him, but I don't think it's improbable that the porn was actually his. Pedophiles are skilled at opsec, keeping secrets and doing unsavory things, so their background suits working in IC if they can conceal their behavior. And if discovered by a foreign intelligence agency, they'd be easy to extort into spying.
Vault 7 released a fair bit of code, didn't it? It would benefit state adversaries to leak that publicly, by burning exploits the CIA's using.
Much easier to trap him in Russia and claim he's a foreign agent.
Character assassination is a common tool in the CIA toolbox.