Yea, it's all very confusing. Technically that link says 1/4" wood is good enough for an ignition barrier, not a thermal barrier. According to safety codes, thermal barriers are what you want to have around actual living spaces. Ignition barriers are acceptable in attics, seemingly because they are separate from living spaces and often have a thermal barrier between them?
I'm not really sure. I know there are a lot of building codes that are legitimate and extremely important to follow, I know there are others that are BS. I don't know enough about this one.
Thoughts are still welcome from anyone who feels strongly one way or the other!