Maybe write them down or something? I mean it's not that great of a philosophy but it's really solvable. :/
This is a huge issue to me and someone needs to find a way to make the safekeeping of cryptocurrency easier and more fool-proof.
Saving a passphrase or writing down a password on a piece of paper is a huge issue for you? or is there something else maybe? Well the way and the level of security of your bitcoins is up to you, how careful are safe you're keeping them that's how safe they're going to be.
Maybe he is just a forgetful kind of guy? and I think this is really bothersome and I have known someone that has an ATM password that is only 4 number that are needed but keeps on forgetting it, he needs the number to always be written in a paper, then keeps o looking at it every time he would withdraws from an ATM machine well it is a nature of some person, well problems like these I think it is pretty normal and since the passphrase was made with numbers and letters with a wide range and not only four digits I think he would need to hide a bunch of written passphrase and put it some where safe,