Per the CyanogenMod blog:
Today, we were contacted by the Google Play Support team to say that our CyanogenMod Installer application is in violation of Google Play’s developer terms.
They advised us to voluntarily remove the application, or they would be forced to remove it administratively. We have complied with their wishes while we wait for a more favorable resolution.
After reaching out to the Play team, their feedback was that though application itself is harmless, since it ‘encourages users to void their warranty’, it would not be allowed to remain in the store.
Android may hold the lion’s share of the market, but it isn’t because of the “open” meme.