I believe it was turned off-topic because you discussed it incorrectly. If it is in the gambling discussion section, you have to discuss matches, win rates, odds, how to bet, which team to bet on. In short, everything has to do with betting, but your topic is quite simple, it only discusses sports. You know, this is not a sports forum, I have no objections when the subject is moved. Sometimes a topic gets a lot of attention, but it's still off-topic.
That explanation would make sense if there is no other Super League themed threads in the Gambling Dicussion board, namely
European Super League? made back in October 2020 and it's still there. From what I could see, it's not any different than the thread started by @igehhh.
My guess is that it's simply moved from there as by the looks of it, it won't be possible to bet on anything related to SuperLeague in the foreseeable future, but still it kinda fits more to Gambling Discussion thread where all other sports discussions are than in off-topic where threads go to die.