Well the nun might have been down drafted but I think you’ve excluded one key reason Beanie would not likely be a suspect...he couldn’t possible leave Cecil behind.
A fair point, but it can't be cheap to feed a pet sea serpent. $200K in 1970s dollars would have kept that big rascal in Serpent Chow for sometime. When the show, comics, and merchandising all went down the tubes, Beany might have been desperate enough to try air piracy. Could have left Cecil with Huffinpuff during the job.
Remember......motive, opportunity, and ability.