You could keep logging out and in again and hope that eventually you would not be instanced with any of the blockaders, and/or you could run a lot of other downloads on your connection to try to force the instancing to put you alone. However if you have a good internet connection, no router issues, and you are not doing that, chances are that you would end up being instanced with at least some of them.
Anyway your point does raise an issue that's also been discussed on this thread, which is that if there was an inherent scoring advantage just from being in open mode, anybody with a dodgy internet connection, or who tweaks their router to interfere with the instancing code, would then be at an advantage. That's why if they did go down this route, it would probably have to be based on something that really shows you were with other players, like wing bonuses, or additional rewards for killing players versus NPC, for example, the later of which will cause a right old ruckus.
The thing is you don't need to logout - once you get into SC you can always throttle back drop out - or in an emergency drop at speed taking damage and a longer cool down - you can then scoot off or re-enter and drop again before anyone gets near you.
There is no need to logout to try to make your own instance.