I mean no offense, but this is sort of, with regard to your principles at least, cutting off one's nose to spite one's face? I get that incremental reform is frustrating, but here you had a chance to enter an org you know needed changes, and you blew it because you refused to take a basic drug test that you openly state you could've passed easily.
Like, it's bullshit that they asked, it is an invasion of privacy, it shouldn't be a reason to forgo employment of a candidate they otherwise liked, but at the same time, it wasn't an issue of like, you wouldn't get hired because of your race or gender, it was an issue of like, you'd have to abstain drugs for a while. And then, once you're part of that organization, you can help push for the exact changes you want to see in it.
It's the same reason I get frustrated with my generation not wanting to run for office: we spend all our time complaining about how awful the government is, but precious few are putting themselves out there as the instruments of that change. I don't know if it'll work out or not but I know damn well it won't if we refuse to even try.