Wouldn't it be better for him to create 1-of-2 multisig wallet involving both desktiop and mobile?
No, a 1-of-2 MultiSig is relatively pointless...
It introduces unnecessary complexity and increases transaction size... additionally, it can make recovering funds into different wallet apps very difficult/impossible.
Either use the same seed on both devices... and have the wallet "mirrored" or "cloned" (or whatever you want to call it.) and both devices will have identical addresses/transactions/balances and you can spend your funds from either.
OR create 2 completely separate wallets on the 2 devices and operate them as independent wallets... in which case, if you want to get funds to the Electrum app on your phone, you would need to create and broadcast a transaction from the desktop wallet on the laptop (and pay the transaction fee etc).