It's the same situation that almost occurred with Jonsteederi and I. I had typed the gotcha, as posted, but I took multiple screenshots in hopes of getting him. However, of the two I took, only in one did he appear still in the lobby (and so I couldn't have said I got him simply because he was in the lobby without a screenshot, as Fangfallen quoted from the rules, but luckily I had one that had him
). I've played this forumesque game in other communities, and it's always the same. If you escape from having someone take the screenshot, then they cannot, by the rules, say that they "gotcha," despite having seen the player and typing the message.
In truth, I did see what he typed. However, due to the lack of screenshot, that is a violation of the rules as they stand, which is how I ended up turning around his unfortunate series of events into a fortunate series for myself (because he just sat in the lobby instead of leaving it).
Now, here's how the events went down. I was, as per normal, playing some 1v1's, because I enjoy them. I was in the middle of creating a new match, had just "clicked" the "create" button, and saw his message pop up as I was exiting the lobby into my game lobby, and so he missed taking a screenshot of me in the lobby with the message. It was then in my favor to back out to the screen where you can go to the shop, and wait a minute or so, and keep checking my friend's list to see him still in the lobby. I joined, entered the message, and took the screenshot as he had sent his message (again).
It was and always has been my understanding that the gotcha game allows one to escape if someone had typed the message but was not quick enough to get a screenshot. If that is not the case, then I doubt anyone in their right mind (who cares enough about winning it) would even enter the lobby on a main account, but purely an alt, for pure paranoia of being caught.