From the parts I watched, I kind of understand why Math wouldn't pay them with the exception of Bigga.
If you weren't s regular initially, you aren't much different than the people who are being interviewed. However, I do think they should have been paid once they were officially regulars. Even then, both said they were given contracts and were paid at times. Another part that was confusing is the signing of the contracts. It wasn't made clear if they signed them or not. They also mentioned Math never signed the contracts, so technically no one could breach the contract. You can't breach what was never signed. To me, Math also isn't obligated to pay them until they signed.
Bigga was said to be Math's security, so I would assume that is what he should have been paid for. It's unclear if Bigga was considered a officially cast member. It also wasn't made clear if Bigga didn't get paid for providing security or if he just did it at a loss. If he gave Math a discount, honestly that is on him.
The new spin is now Math was upset that his music wasn't being pushed. Now this doesn't make sense to me given Math has a platform to push his music. I get wanting the classic DJ cosign/push, but why not do exactly what he recently did and push his music through his channel. If it's good, it would have made it to Clue or whoever else anyway. Now this could have also just been hate because they aren't cool anymore, but I got the impression that Math's music wasn't good. If that's the case, Esso should have been upfront about it.