@OP
If you feel your question has been answered, please lock your topic in the lower left corner of this thread (click 'lock topic').
The seed in question is not a bip39 seed
You obviously weren't even able to read the OP properly:
If you would have clicked on the link, you would have seen that it indeed is a BIP39 seed.
No one is claiming cross wallet compatibility and you can't rely on that.
Compatibility is a big pro regarding BIP 39 seeds.
You can definitely rely on that since multiple wallets do use BIP39. And even if you don't want to rely on other wallets, you always can simply download tools to convert from BIP39 to private keys.
To add to the above to use it as a bip39 seed you have to turn off checksum checking and that also means that typos in seed entry/seed notation can go unchecked. Then there's the question of the derivation path. You have to note that down too. So overall if you make a copy of the wallet file it'll contain everything that electrum needs to know to recreate your wallet and you don't have to rely on an human's getting it right.
The derivation path is not that hard to find out..
Legacy:
m/44'/0'/0'p2sh-segwit:
m/49'/0'/0'native segwit:
m/84'/0'/0'Its not really necessary to write it down.. this information can always be found with google within 1 minute.
A copy of the wallet file has a way higher chance to get corrupted than a proper handwritten backup. Such a backup is inalienable. While a backup of the file definitely is faster to restore, it is no way that reliable.