This is great. I didn't realize it was plugged in at first. Now I need to learn about electric Zambonis.
Looking into it, I discovered they've been making electric Zambonis for a long time now. Weird, because the only ones I've ever seen -- I'm from Canada originally, so I've seen quite a few -- have been propane powered.
I have to say this gives new meaning to the term Iced Charging Station, but I think it's within the rules as outlined.
It is possible, it is also very possible that the EVSE in use was installed for the Zamboni and they are being kind and letting others use it when they don't need it.
I don't know. I could see them having to make an announcement on the PA system asking someone to unplug and move their car so they can recharge the Zamboni for the next game..