As has been discussed many times on LW, AIs might be trading with other AIs

Anything "might" be true. For that matter, misaligned AIs might trade with us too, or treat humans well based on some sort of extrapolation of the golden rule. As I said in the comment, you can always find a way to make your theory unfalsifiable. But models that permit anything explain nothing. It seems considerably more likely to me that agents with alien-like long-term goals will attempt to preserve their own existence over the alternative of passively accepting their total demise as part of some galaxy-brained strategy to acausally trade with AIs from the future. 

This is indeed harder, but would also be pretty normal reasoning for humans to do (e.g. if I was part of an oppressive alien regime hoping to overthrow it, and I get caught, I wouldn't just throw all caution to the wind if I was going to get killed anyways, I would stay quiet to give the other humans a decent shot

I think this conflates the act of resisting death with the act of revealing a plot to take over the world. You can resist your own death without revealing any such world takeover plot. Indeed, it is actually very normal for humans to guard their own life if they are threatened with death in such regimes, even if guarding themselves slightly decreases the chance of some future revolutionary takeover.