The only problem i see about this and that dont really fit is the whole drugs things, if Quinn is involved with the drugs with the Diks why whould she fuck them over?
I think there's a bit of confusion when the subject of these pictures come up and some people seem to think that the theory is Quinn is behind all of it, but that's not the case.
The Cathy picture is what people think Quinn is responsible for, because right now the Alphas are under increased scrutiny from the school because of the incident with Chad and this is likely to cause an issue with Quinn completing her order with the Alphas. In order to get attention off the Alphas, she either personally leaked that pic since she likely has a lot of free-reign to roam around the DIK mansion or she had someone like Riona do it. The scandal this causes would get the DIKs in trouble and it would either divide the scrutiny of the school between the Alphas and DIKs or put it solely on the DIKs for a short while giving Quinn enough time to complete the Alpha order without being noticed.
The blackmail pictures, however, no one really knows who's responsible for that and even those who believe in the Quinn-Cathy theory do not think Quinn is behind it because it serves her no purpose.
The other common misconception is that it couldn't be Quinn because it would hurt her business, something that is often proclaimed by those who denounce the Quinn-Cathy theory. But Quinn, in her cocky arrogance, does not think she will get caught and even if she did, she'll likely get off lightly by brushing it off as a prank or blame it on someone else like Sage or the MC. It could backfire on her, but likely not in any way that will permanantly harm her business or relationship with the DIKs, and she's certainly not intentionally trying to do that either.