Sounds a bit like psychobabble, frankly.
But I will try to parse it into something more intelligible.
They are basically saying that you download the whole blockchain. That is the record of the public ledger. Then, you are looking for certain strings inside of the blockchain itself and using a set of keys to get additional keys. If… I am understanding properly.
Basically, that the blockchain and its record of transactions are part of the deadman's switch.
It's a neat idea and not entirely implausible.
But you're going to have to dive pretty deep into how those programs and protocols work to do it yourself. Could be something. Could be a goose chase.