User-generated content is the stuff of "hacking"gold. The occasional big-cheater battle may not be so fun to some, but there are probably some masochistic people who prefer their opponents come incredibly strong: Basically, hacking is more a thing of preference.
Steam had a pretty unfriendly approach to deal with hackers: some FPS games just banned any use of user-generated content in online-battles, period. Now this is good for a by-the-book battle, but now they can't even use the "skins" they created. (Skins are a cosmetic hack that only changes their character's model, it usually affects nothing.)
Besides that, hacker players who created all kinds of custom rules and items won't be able to use them with each other anymore, even if it's just a one-on-one thing. That strong-arm approach to making the game fair ruined the game for content-creators, who are otherwise encouraged to make stuff with the dev tools included in most games.
To me, hacking a contest, event, paid-for tournament or any thing with more than four people probably isn't a thing of nobility, but the overall world of hacking is fine - sometimes even majestic. People have that right to beat their games at their own pace, even if it's just a step or two, even if it cuts down the systems and work expected of them. They've purchased the game and thusly reserve that right to play it their way.
But if it's against someone such as yourself, who neither expects nor asks for hackers to come and overpower them, the annoyance of them is shared and the people aren't so noble. You could put up a note like "hackers need not apply." if it's that frequent.
