No, they are correct, because the deciders themselves are just a cog in the proof of the overall theorem. The specification of the deciders is not part of the TCB, so to speak.
I'm pretty sure this is a feature that's available at least to big creators – I remember a Tom Scott video doing a bit involving scheduling an ad at a particularly fitting moment.
You might have to be a YouTube partner or something like that to make use of this stuff, though.
I have heard of at least one instance of an exam a while ago, where some questions – ones that need diagrams in their statement – would be written onto the blackboard in the exam room, due to limitations of the duplication techniques used for the exam paper.