Let's use the current alcohol ban from the Federation as an example. Let's say player group A wants to enforce the ban and group B wants to thwart it. So B drops into Solo, smuggles tons of alcohol all over the place, spikes the Eranin rum sales through the roof. Meanwhile, player group A sits in open play and stops NPC smugglers...
Now the in game story has been dictated by the solo/private players' actions while the open play players have accomplished little to nothing because they couldn't stop the smuggling.
This is an exaggeration to prove a point but 50 pro-Federation players in Open play can have less of an impact on this scenario than 5 solo/private players smuggling booze. Is it fair to dodge gameplay, influence galactic events, and change the course of the story with nothing to directly oppose you?
I think this misses the point that there are no single, persistent locations in the game. The celebration booze is being made in Eranin and Wyrd, presumably flowing through their respective stations. But those two stations don't exist as discrete, single locations. The game will generate as many different copies of those stations as are needed, to fill the traveling Island instance bubbles of the players who go there. Multiple Azeban Cities, multiple Vonarburg Co-Operatives. And not just in Solo Online, but in All Online too, depending on how the P2P matchmaking server loads players into their overlapping bubbles.
You can't blockade those stations, except in terms of a loose statistical chance that your players are a little more likely to show up for other players if they congregate in those systems. Like Freeport is working now, and notice that many players in All Online say they never see other players there, because they're at a different Freeport! Geographical separation is probably a factor here too, with players in places like Australia less likely to be matched with players in the UK/Europe in the same instance, due to lag issues.
Bottom line: It's an instanced game, not a single server where emergent, player based territorial control makes sense as a rationale for forcing everyone into PvP mode.