And release a statement that they are testing this new filter, and have signed all politicians up for a trial. Randomly block about 10% of their traffic, and also some porn sites. Slow down their download speeds, and triple the prices. Anyone who publicly supports the filtering will of course get added to the trial.
Technically, a single company can have products licensed for both closed and open licenses - I know, I work for one. They can even offer the same product under an Open Source license, and under a different license. Owning the copyright, they can fork the product, implement some features only in one version, and release that only under a closed source license.
Of course, nothing prevents anyone from taking a version that has been released under an Open Source license, and (re)implementing the features the company only offers under a closed license. Except that it requires time, effort, and know-how.
An order of magnitude???
In rough numbers, the mass of your normal human is one order of magnitude over the mass of the rover. The life support for said human would be another order of magnitude, or two. That would be fine, if we could leave the volunteer(s) behind on a dead planet. But getting them back would mean sending a big enough ship to bring them home. That would be at least thousand times bigger than what they'd need to survive on the surface - three more orders of magnitude. That's what I could think here and now. I believe there would be a few more problems to account for one or two orders of magnitude. So, my estimate for sending humans (that would expect to return) would be at least a million times more than to cost to send the rovers. With all these uncertainties, perhaps a billion...
Still, worth the effort, if and when we have the resources and technology. I hope to see that in my lifetime, or at least in the next 50 years!
The sooner you fall behind, the more time you have to catch up.