As @hilariousetc said, in general this sub-board was made just for signature campaigns.
It wasn't made
for signature campaigns, but rather as a consequence
of them.
I get it now but still for a topic to become lively you need audience/contributors. Sport and gambling go hand in hand. The gamblers are mostly interested in events they can bet on which sport happens to be one of those events. Therefore, they discuss more on sport-like events, which also help them with their gambling skills. The more you get familiar with which team, player, boxer, wrestler etc is in form, the greater the chances of placing a correct bet.
It can be lively in off topic or a sub board of it, but this is still irrelevant. Some people bet on the weather but you shouldn't be merely discussing whether it's sunny or raining or not in there. It's like saying discussing Nike shoes belongs in Gambling because an athlete might wear Nike footwear. If it's not directly about gambling then it's just sports discussion and that's off topic.
Suggesting that such topic to be moved to offtopic won't be fair to the users interested in such discussion. I'll choose this sport like discussion irrespective of whether they're offtopic or not, over the generic topic (spam) more associated with gambling like "Do you gambling in the morning or afternoon, Do you lose or win when gambling, Is gambling good or bad, Is your family aware that you're gambling etc".
Why would it not be fair? Why does it matter whether the topics are in Gambling or Off Topic? It doesn't. The only thing it would effect was being able to get paid for posting in them if the campaign they're in doesn't pay for posts in Off Topic and that seems to be the whole crux of the issue. There being other spam threads in Gambling is irrelevant. There's just as much spam threads going on in the various sports discussion threads at the end of the day. You get hundreds of people writing generic lazy stuff or talking about things they have little to no interest in. I even remember someone creating a thread for some sort of women's sports tournament and in it they even alluded to the fact that they're not interested or know anything about it. That was clearly another thread made just to post results or whatnot because it's an easy way to rack up your sig posting quota.