How to stop my autistic brother swearing

Hi, my brother is 15 with limited speech. He’s obsessed with Spongebob and has been for many years and he came across these videos on YouTube where Spongebob clips are edited with swear words being shouted out. 

My brother has been copying. He mumbles the words under his breath or he shouts them out loud just like they do in the videos. I’ve tried removing YouTube and blocking it from the devices but he gets so stressed and he has meltdowns because he wants me to ‘fix it’. When I say don’t say those words, they’re ‘bad words’, he doesn’t stop, he just repeats the words ‘bad words?’ 

He doesn’t understand the meaning of the words and saying that they’re ‘bad words’ doesn’t mean much. He knows he shouldn’t be saying it but he says it anyway.

Does anyone have any advice?