If his Electrum version is 4.1.0 or above and he has another regular wallet(s) then I wouldn’t advise him to use a generic password.
The reason is because Electrum (mobile version) since version 4.1.0 no longer allow users to set different passwords for different wallets. So, if you update the password for one of your wallets (the watch-only in this case), all your other wallets will be encrypted with that new unified password.