The examples from the wiki describe situations where the initial source was legal, but protected. E.g., placing a sting in the path of a suspect on the word of a protected informant, then omiting the reason for their 'luck' in finding the suspect. Or e.g., withholding NSA wiretaps from DEA until the citizen or geography of the source is determined to be foreign (unethical, but not illegal).
Yes, but in this case, mass analysis of Tor traffic by the NSA could have thrown up a suggestion to the FBI "if you want to find the real source of the servers, all you need to do is exploit the CAPTCHA servers". The activities of the NSA don't have to be illegal for the FBI to obfuscate how they got to the final result. I doubt the FBI spent load of time just hacking around. The Government started with the problem "how do we reveal the true source of the Tor anonymized traffic" and fitted the solution to identifying it to some fully legal and totally unnefarious. It is in the Government's best interest to make criminals think they are incompetent.