In the games I've played, the Psychic Maelstrom is usually a Front, actually, but sometimes it manifests as a Threat in specific circumstances.

In the game Tony Dowler ran, for example, the Psychic Maelstrom was the ghost of the past, which we could reach through playing rock music.  When our Hocus-led band played "Helter Skelter," we used augury to accidentally summon Charles Manson into our apocalyptic future. Charlie became a specific Threat (I think, since I wasn't running it), but he manifested from the Maelstrom.

Likewise, in my current game, the Maelstrom is related to the restless echoes of everyone who died in the apocalypse.  That's all we know at this point, but those echoes have already manifested in a number of ways, driving at least one member of the quarantine's stasis insane, haunting our faceless and now our quarantine too, and making our touchstone crazy until she learned to control the voices in her head.  Those are all threats, potentially, that are related to the Maelstrom as a front. 

Then again, when people use augury or other moves  (open your brain, healing touch, visions of death, etc.) to interface with the Maelstorm, sometimes the Maelstrom acts as a threat and makes threat moves when they fail.