From: metro Chicago, Illinois, USA
I recently played the TOAW Papua New Guinea scenario hot-seat solitaire. Quite enjoyable.
In my nearly 50 years of board and computer war gaming, the vast majority of my games have been hot-seat solitaire. (Some AI play, when the AI was "good enough", which isn't often enough. And just a very few times against a real human opponent.)
Hot-seat solitaire is not for everyone, but if you have no difficulty pretending ignorance, can set aside favoritism for one side or the other, and if you don't miss the social and competitive aspects of gaming, it can be fun.
Moreover, there are some scenarios with no PO, that are "designed for PBEM only" (e.g., the PNG scenario). If you don't have an opposing player (maybe because the scenario is so obscure that it's hard to find a suitable opponent with the shared interest), or you simply won't do PBEM (as in my case), what will you do? If you want to play the scenario/subject badly enough, hot-seat solitaire is the only alternative.
Would I give hot-seat solitaire a second chance? Yes, of course.