It's fine to say "I don't know what's going to happen y'all
" instead of stringing together thin excuses
First of all we're already in uncharted territory with somebody under contract outside the E appearing on their programming. Second, champions aren't usually in rumbles, third they announced her entering as champion, fourth she's sitting on WWE.com with Knockouts Champion next to her name. So nobody knows what's going to happen.
Since WWE themselves acknowledged her as champion and wrestling elsewhere, there's not too good of a reason for her to not have the belt with her. And even if she didn't, again, WWE already put everyone onto her current run on their show.