He won't have to broadcast the transactions using his Electrum server if he doesn't want to. Chances are that some or all of the peers he connects to won't be configured to consider sub 1 sat/vByte transactions as valid anyway. The most important thing is to sign the transaction using an Electrum server that supports it and then you can copy/paste the raw transaction using mempool.space's broadcast transaction window and broadcast it from there. That also ensures that the biggest mining pools add your transaction to their mempools.