Reading that preview, I found it hard to imagine the actors' voices and deliveries as I read. I mean, TNG was so sedate and orderly and measured, and present-day Who
is so frenetic and goofy and melodramatic and loud, so it's hard to fit them together in my mind. Although come to think of it, I suppose if it did actually happen onscreen, it might go kind of like a Q episode, with this wild, bratty trickster figure barging in and disrupting the staid, civilized rhythms of the E-D crew. Come to think of it, the Doctor has a lot in common with Q, aside from having kinder and more benevolent motives. I think Picard would be wary of him because of that, and would take a while to learn to trust him. Maybe we're seeing a bit of that in the preview, though I don't yet know what came before.