It's not so much scripting as Alan and Bill won't let a word in edgwise. I wouldn't cut them out of the show, but 99% of their shtick is mocking Stephen's poshness and making growly noises.

I believe he was a last second guest, everyone else had a chance to prepare and riff off each other, they just kinda threw Hodgeman in as a 5th wheel. It was a waste of a perfectly good panel appearance. This QI clip gets a terrible 5 star rating. Rich Little is their usual the token American, he does a good job.

Also everyone except the woman has either been on dozens of episodes, or been on every single episode. They even have their pet QI facial expressions down pat.