@OP Since the USB Drive has a short lifespan I suggest burn them into CD/DVD because they have a long lifespan according to Google 10-15 years but if you want a disc with a longer lifespan check the M-disc it has a 1000yrs lifespan. And don't forget while creating a wallet to make sure it's safe you should create a wallet in an offline environment to avoid someone monitoring and recording your keystroke/clipboard.
USB drive has expected lifespan of 10 years which I do not think it is bad at all.
What makes the lifespan of USD drive, CD, DVD, SSD or HDD shorter or longer depends on how often you are using it to transfer files, also maintenance. If he he using the USB drive for just file backup and nothing more, I am expecting the USB flash drive to have a long lifespan if he protects it.
I do not see any reason of depending on flash drive when he can use BIP39 passphrase and backup the seed phrase just on a paper.