It might be a variation on an idea I’ve thought about myself. Goes something like this:

Spend a small amount of BTC automatically to an “anyone-can-spend” address with a timelock for 50 years worth of blocks from now. Do like $1 worth every on-chain transaction. Then it will get unlocked at that block height, and any miners can then scoop it up for themselves like a fee. If Bitcoin does 1000x in purchasing power over 50 years, then that $1 will be the equivalent of $1000 in today’s money in fees for future miners.

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No idea if that’s what he is talking about, but it sounds similar the way you described it.

(If you have a link to where this was explained I could look into it)