Option to ban factions

I recently discovered that Unfallen vines slow down one's ships, thus making it all but impossible to conquer them while still protecting one's own systems. (While I take five turns to travel, they take two and therefore wreak havoc upon my nigh-defenceless systems.) Because the only other option is building more ships, which would, unfortunately, result in a near 100% majority for those silly militarists, I feel like the best option is simply to keep them from spawning in the first place. 

I am well aware that it is possible to choose all factions, but that's no fun, I'd much rather be able to ban whichever faction happens to be giving me a headache when I start any given game. (I'm not sure whether this is already implemented, but if it isn't I'd really appreciate being able to ban duplicate factions, or alternatively keeping the number of duplicates to the lowest possible number, if there are more factions in the game then there are unique factions.)