I Don't really know, since I haven't seen those last episodes in some time.
But it does help to say that the writers never were comfortable with Bean to begin with. I wrote a post about it a while ago, but to get straight to the point, he always seemed like he was the extra character in a scene, and seemed to be alone a lot of the time (I.E. The Transcontinental Whoo Whoo). Other than, maybe The Next Generation, where Skeeter (who was mad at Scooter at the time) hung around with him (turning him into R2D2 and Elroy Jetson) I have yet to see an episode where he was used to any capacity other than just saying a couple lines. He was no doubt created through the pressure of someone at Henson wanting to expose Bean as much as they could (before Steve took on Kermit, Bean seemed to be his main character for a while)... then there is the rumor that the head of CBS's kid didn't like Baby Bunsen or Baby Beaker, and they disappeared. And somehow they felt they needed to close that gap, which honestly, Statler and Waldorf did better (supplying educational backgrounds and content)