The issue here is that MEGA presents itself as "the privacy company" and makes some very careful claims about encryption: All files stored on MEGA are encrypted. All data transfers from and to MEGA are encrypted. And while most cloud storage providers can and do claim the same, MEGA is different – unlike the industry norm where the cloud storage provider holds the decryption key, with MEGA, you control the encryption…
If the government has compromised trusted CAs to do man-in-the-middle attacks, my thought is that they are only for 'intelligence' levels of actions, at least at this point in time. The government isn't going to tip its hand to foreign adversaries even to jail a few pedophiles (or other breakers of Federal law).
Maybe you missed it, but the DEA already uses the questionable NSA secret surveillance to find drug dealers, and constructs evidence against them to hide use of the surveillance.