I allow dues ex machina if the force responsible is just that capable to begin with. Like a character such as Q, who really is just a deus ex machina/trickster. He bends rules, can do whatever, but that is his role. I just hate it when anything and everything can do stuff like that. Recurring aliens in Doctor Who at least are held to their explanations more than once, instead of just being one time whatsthatnowguvnor magic. Normally the aliens do have a trick tot hem, both powerful and weak, so it works out.
Either way, this episode was better than the last and the preview for next week looks good.