Ubuntu controls the PPA. Ubuntu has reassigned the developer that largely lead the Ubuntu Mozilla integration. There is little we as Mozilla can do to control this. If you need this resolved complain to Canonical management or find someone from the Ubuntu community of Nightly/Aurora users who wants to own keeping the PPA running.

There are precompiled tarballs available at nightly.mozilla.org and aurora.mozilla.org I have used these on just about every major distro and several of the smaller ones without issue.