I have no idea what a "true Unix" is. Perhaps he means the "One True Unix," which is of course the one developed at AT&T/Bell Labs. Frankly, the whole topic is too religious, and you're right to be ambivalent.
So anyhow, about Fink. Get it. Try it. It won't be as easy as drag-installing Explorer, but it's really not all that hard. The included "dselect" utility makes it a joy to use, and if you prefer an Aqua interface then try FinkCommander.
In short, nothing on your computer will be harmed by installing Fink, and if you decide it's not fun or valuable you can just delete the /sw directory and it's gone, gone, gone! (well, almost gone, cuz you might have some dross in your /Library/StartupItems folder if you mess with "daemonic.")