How many people outside of his fellow white supremacist types knew that certain numbers could have such connotations, prior to this scandal? I certainly didn't. If I'd have seen someone with an "88" tattoo, for example, I'd have assumed that it was e.g. their child's year of birth (or something). Or that they were a fan of the "two fat ladies" bingo call.
Hopefully, the entire production staff of this programme doesn't include any white supremacists. Hence nobody picking up on any possible connotations of his tattoos.
If people have distinctive tattoos visible then the meaning of those should have been given more than a passing glance. It doesn't even need to be things readable in English, if someone has something offensive tattooed on their forehead in a foreign language or script it should be independently verified what the meaning is, not just taking the participant's word for it that it's saying "peace and love to all" and they got it while drunk in holiday.
The 88 on its own I could imagine easily passing a cursory check, but the reason for it doesn't, and then there's the other tattoos which all combine to tell a story that is easily checked with a simple Google search.
This is not a case of production staff not being white supremacists who therefore couldn't notice the references, it's a case of production staff not doing basic checks on their participants.