It seems that staple-bound books are now being classified as TPB. It could just be in the cases I have seen, but it seems curious. There is an option for staple-bound. Why not use it? The two examples I have at hand are the first printing of the Cerebus Guide to Self-Publishing and the Powers Encyclopedia. Both are packaged like standard comics, and both used to be listed as staple-bound but got switched to TPB.
Also, Powers Encyclopedia should be moved to comics, if you ask me. If OHOTMU and Who's Who are comics (please don't move them), then so is this. It is words and pictures telling a story, or at least fleshing out backstory. A story doesn't have to be a narrative in any strict sense and doesn't need to conform to any standard style to fall into our definition of comics. Epistolary novels are still novels. I'm not trying to open a big can of worms, and I'm not trying to make the argument that any magazine with illustrations should be a comic. I am just trying to appeal to general comic common sense and consistency, and want to make sure everyone is on the same page, so to speak.