Why is it "ultimate bravery"? Unless you compile your own kernel, the Linux kernel many of you are using right now is "arbitrary". That is, someone else compiled it and you are trusting that what it will do (or initiate, via init, for example) when you boot it is acceptable. My guess is most Linux users do not compile their own kernels.
Perhaps the problem here is not that these project "developers" are suggesting that others pipe unread scripts into /bin/sh, it's that too often these "developers", or the others on the receiving end of their scripts, have a poor understanding of shell scripting.
I find in the majority of cases where someone wants me to run their shell script, I could do what needs to be done without using the script or rewrite the script myself, using a minimal POSIX-like shell instead of bash or ksh, and reducing script size by 90% or a similarly large percentage. Then there's the minority of cases where I actually admire the care that the script author took to make the script efficient and portable, or where I actually learn something new by reading the script. That happens all too rarely.
While I'm on the topic of shell scripting, I'll add that I do a lot of shell scripting for my own personal use. Since no one else ever has to read my scripts, I take the luxury of ignoring the Shift key and write all my scripts in lowercase. I have no need for uppercase variable names; they only slow me down.
I note that djb also writes his shell scripts in lowercase. For whatever it's worth, I consider him to be one of the world's best open source programmers, and a competent shell scripter.