Try making use of cake wallet to load up the seed or something like unstoppable wallet so when it syncs you can see which coins are on it. I doubt it would be bitcoin though...
I guess he would have used Electrum or BIP39 wallet for it and it would have worked if it is a BIP39 seed phrase.
If bitcoin is not there, he will still be able to import it on Electrum but the balance will be zero as long as it is a BIP39 seed phrase.