For years, I have put my MacBook Air and iPad in a bin together. As long as they are not stacked, it has always been fine. Not to say things couldn't change, but I would expect tablets to be treated the same way laptops have been historically.

Also, if they do need separate bins for all of these items, they'll run out of bins faster, which would be a pain for the TSA employees. I expect that if interpreting the rule strictly creates a hassle for the TSA employees (who have to cart the bins around), they won't take the strict approach.