Can I Plug?

I was at Starbucks today and happily found 2 plugs in the wall to use because I needed them.
I had my headphones off - hoping to deter any comments/questions/conversations/anything requiring my acknowledgment as I worked to restore my computer.
This weird little man comes and sits down with me and tries to talk with me and I mean WEIRD. I tried to pretend I didn't hear him the first time, but he actually waved at me in front of my screen.
He said I see you're working hard and the internet is working. HUH?
I have an air card, but I didn't get into that. I barely smiled and shoved the ear phones back into my ear hoping it was a sign I did not want to talk.
Then he waved me again and said "can I plug? can I plug" pointing to the plug.
Normally I have more patience than this, but if I'm plugged into both sockets don't you think there's a reason? There are no signs in Starbucks that says I need to SHARE. AND he did not purchase anything. I bought an effing six dollar frappa something or another just to use the plug & be left in peace.
Because of his frantic waving I ended up leaving and sitting in my car going about my business.
Why are some people SO clueless?