Earlier quoted context omitted.
There is a vast community who thinks it's bad, and unsafe (with examples on how to detect direct piping to bash in order to serve malware) and a few ones condoning it. That seems like saying there is currently a debate on the roundness of the planet Earth.
Ultimately, the only insecure thing about curl-to-bash is if you don't trust the server — the server in this case being Github. I think few people or companies include Github-being-malicious in their threat model; if Github was malicious, any build artifacts produced by even cloning from Github would be potentially suspect, since Github could fairly easily detect automated build agents and serve them different conten…
If it's okay on GH, we train the user to think it's okay on less secure sites.