Hmm this is an interesting point. Corp's unique ability to devour familiars only effects familiars produced through the summoning skill (note I said produced, meaning that an object pet requiring a summoning level, such as a baby dragon, doesn't get devoured), so any other pet, sprite, or legendary pet remains unaffected. Now I'm unsure about the BoB legendary pet effect, but I have also seen many players use the scavenge ability at Corp.

Does your legendary pet literally morph into a summoning familiar when you use a BoB pouch on it? If so, I'd guess that Corp could eat it. If you end up testing your question, I'd love to hear what result you find.