Simple. It's a legal grey area. Super User doesn't want to build a reputation for encouraging something that may or may not be illegal, so it was decided to stay safe rather than sorry.

I have actually proposed to have the tag banned [here](https://meta.superuser.com/questions/1381/banned-tag-proposal-hackintosh) and given some more reasons why.

> [**Sathya ♦**](https://meta.superuser.com/users/4377/sathya): There is no reversal in status. This answer still holds good from a moderation point of view.