Have you tried sorting by “Read time”? That should let you quickly see and select a list of all the users who haven’t spent any time reading.
Your suggestion is interesting but I am a bit concerned about automatic deletion of users just because they completed their profile and haven’t read yet. The users flagged thanks to this setting are hidden, so any harm is already taken care of immediately.
I think the answer here really is to revisit this setting and improve it. Now that we have AI spam filtering, it should be possible to filter user profiles for spam. Just disabling or deleting everybody who completes their profile feels like an overly blunt response to me.
You’re welcome and sorry! 
I came across it when researching the “Approve suspect users” setting, which is not well documented yet here on meta.