They still don't know the source of the communication. Running an exit node means they can see where traffic is headed as it emerges from Tor, not that they can

They still don't know the source of the communication. Running an exit node means they can see where traffic is headed as it emerges from Tor, not that they can magically determine from whence it came. The problem here is that the destination can identify you. You, after all, are the one paying for that VM instance at that IP address within AWS. Who else would be connecting via SSH?