My FFE doesn't fast charge but I have unplugged many a PHEV when I needed the L2 charge to get to my destination. I've even parked blocking them in because I had to in order for the cord to reach. I always babysit my car in this situation so I can move to let someone out if need be. Then I just plug them back in when I leave.
If I was at a fast charger that charges by the minute I'd probably be happy someone unplugged me at 97% My rule of thumb is that I only unplug someone if I really need the charge or it appears their car is done charging. When I was in jmueller065's neighborhood at a one outlet charge station I even plugged in a car that had parked next to me when I left and it was obvious they were waiting for me to finish charging. I just try to be as reasonable and courteous as possible. Inevitability though you'll inadvertently piss someone off. I picked up one of these hang tags
at an EV event and usually put it on my dash to try and let other's know if I care being unplugged. I never put when I'll be back though. That just advertises to thieves how long they have to go thru my car before I come back.