Q, anyone?
One way I thought you could interpret that is that the wormhole aliens in fact only exist when the wormhole is open - their existence is only in those blinks of reality that they perceive, and as a result to handle the universe they have a vast predictive ability that looks like future-knowledge.
A robot with an advanced electromagnetic mind-control device... Or just a hacker hooked to Picard's Borg implants/bio-receivers. Or mental illness.
> DS9's first episode has a space alien organism living inside a permanent wormhole and it speaks to you through mind visions, exists at all points in time and can read your mind, put you in your own memories, etc.
They might be lying, or just think it's true. Or again, mental illness. Perhaps we're just seeing Sisko tripping balls.