1. It's not. Given our specialization and current set up, we might just create robots to do the spying for us. Androids if you want to have human look a like's. Besides, why would we need a human prescence at all, the humans civilization is heavily digitalized. If we control their networks, we control them, if we blast their networks out of the sky, they're crippled.
2. We want to keep them on a friendlyness level where they won't bomb the entire planet to get rid of us. Or go and tell some of the aliens.
3. It seems to much of an investement for me for something that will see so little use. If our spydrones get captured, I'd rather give them something they can use to blow themselves up. Our race was nearly eradicated, we should stay undetected as long as possible. No doubt their are beings who would blow up entire planets to get rid of us.
4. And you'd think the GM would let you have an undetectable, mindcontrolling bioweapon?
5. I do, as do the 2 people above you. Also, Hollywood plans seldom, if ever work.
If we want to do control humans, we should either follow Criptfeind, or design a Hivemind resonator thingy/ to allow us to project our physic abilities much further and control the humans that way.
What would be better than destroying the humans' communications would be controlling them. The first step in that is to find out how much of it is satalite based or direct transmission.
Most likely most of their communications will be sattelite based, as Mars doesn't has a large enough population to justify land lines. The Martian ionosphere is not shielded from solar winds, which makes radio communications unlikely, as they rely on the Ionosphere to bounce back the signals.
Besides, the comms we're interested in, Interplanetary, will all be sattelite based. While taking control of them may be good, we will want to cut of all communications in a swift strike when we decide to attack openly. Whitout blowing up the orbital sattelites we will not be able to prevent them from getting out a message.