My school is blocking pro-gay websites, but not anti-gay?

I searched some pro gay websites on my school's computer, and they were all blocked. Out of curiousity I typed in a anti-gay website (peoplecanchange.org) and it wasn't blocked at all! I checked another anti-gay website and the same thing happened. I told my parents, but they're phobic so you can obviously guess what they had to say about it. I really wanted to look up an article, but now I couldn't. Is this wrong, and is there anything I can do about it? Is this illegal?