Sorry for the confusion, but I tried several times to do it as described in the article. The only difference in the output is that I no longer have to/can enter my hard drive password, but the error screen appears directly.
The mentioned article is only relevant if one wants to use unencrypted boot.
The reason for wanting this is an old issue with grub having nonexisting or poor support for decrypting LUKS2 - I don’t really remember - the article was intended to help those suffering long loading time during decryption phase.
I vaguely recall reading that grub has gotten luks2 support so the article may be obsolete.