I think the club are right to issue the ban, just in this case they have targeted the wrong person, ie the person that didn't go and apparently didn't know his ticket was being used.You assume correctly. The chap who used the ticket always buys their tickets.
As I said it doesn't matter now as it's nearly done. Just slightly worrying the club have gone gung-ho on issuing bans again because they are selling out every week. They did the same when we had X'000's on the season ticket waiting list but soon changed their tune when that disappeared and people stopped renewing post covid