The general gist of the idea is that it will be a permanent Spirit gateway, with its control entirely in the hands of the Manticore and his agents - he might give control over to the Crown, but I wouldn't count on it. The leading rumor is that Manticore would bring over all of his Spirit allies and use them to further increase his personal hegemon here, but I have no way of knowing that's the real motive without meeting the man.

They're going all out for sourcing their supplies, including gold from the original King Solomon's mines, and I have no doubt that whoever controls the device could do whatever they wanted with it.

Oh, and obviously, points to Malik here, the Knights will just straight-up murder any Traveler they find investigating it.