Nickelodeon could of flat out said no and not allowed them to animate it whatsoever. Because yeah that's the thing: regardless of whether or not it's the end of the show and there isn't going to be any more episodes made, if it's still something in production that's going to be part of the network (remember season 4 was made to air On Nick as the episodes were completed before the online move. And even online the case remains the same) the execs still can veto and ban something from airing. Why do you think the Angry Beavers episode 'Bye Bye Beavers" never got made outside the VAs for Norbert and Daggett doing a table read of the script? Nickelodeon always has last say on what makes it in, which is why the creators even had to go online and confirm it: because they knew it had to be subtle enough to make some people guess so it wouldn't be autoamtically seen as the two being in a relationship. The team did the most it could that could actually make to air and honestly if you want to see more there are so many images and stories online that are now with the canon couple. Honestly for me just having them say it and that ending is enough because I know that was the limit and I appreciate them hitting it and don't need anything else.