More Words, Deeper Hole

The Doctor and Donna appear to have been catalysts, moving the action forward faster than our PETAoid fellow might have initially intended. Also, the intent, partially telepathic listening they did to the captive "wild Ood" appears to have focused the Ood throughout the complex in some fashion, so that also could have impressed our Chthuluesque innocents. The Ood are a little fuzzy on the individuality of beings, so they might not even have noticed PETA Lad being digested. Or they might even have considered it a good thing, along the lines of "Hey, he wanted to save us, he must want to be one of us!"

Of course, it's the Whoniverse. It need only make sense when it wants to.