No, you're completely wrong.
The key is available in multiple places and has been available for a while, so there is some verification that can be done.
The binary will be checked by gpg, it shouldn't matter where it's from.
Finally, if the recommmendation is to run curl foo | sh, the bash script can literally not be inspected.
And of course you can inspect the bash script (not that it does you any good), curl > file; bash file. It's just that most people don't so that's not what is recommended .