Single player for me. I want to be able to play at a slower pace and enjoy every aspect of the game. In my experiance, MP is too fast a pace for that.
Plus I have (3) children (3) and under, so my game time will be sporadic.
Find a remote world that no one can see and build your robots there. I don't think it's fair of them to say that you can't do one thing when a whole host of other techs can cause end game crises not only robots.