Thanks Ellen. You have pretty much got the process. There is a lot to consider when taking action. Yes, if an email bounces then the account is closed straight away. What happens to Private profiles depends on if there are other people on the Trusted List.
There is a significant number of inactive Profile Managers who upload their trees as a completed work and who probably just wanted to have a place online for it. They then remain inactive until such time as someone needs to access a profile. To close their account summarily would certainly generate some ill will with them, and as we used to say in the retail game, one unsatisfied person will tell 10 others about their experience, satisfied people rarely tell others unless asked. Bad press hurts WikiTree.
A waiting period is necessary because many people may not be available at the exact time we send a message (and other attempts may have run foul of Spam filters and not be seen). This only need happen once though. If a manager is shown to be inactive and has been for an extended period, their account will be closed.
I accept the comments about an automatic process. That would be good. The problem with that is that automated processes tend to run foul of Spam filters (too many of the same message). Quite a few of the emails sent out as a result of UPM requests end up with a response like "Sorry, their request was in my Spam folder".