The setup package is built on a virtual machine serving just this purpose, not doing anything else and running on a Linux
server inaccessible from the internet
. I would also be very surprised if it was infected and the infection was not reported by my other machines running partly NOD32 and MSSE which both score pretty well in the antivirus software
tests. From a quick search it looks like Avira reports false positives for this particular trojan in other SW as well.
Further, the uninstaller is generated on your machine during the installation
, so any infection in it can just originate from local stuff or VERY sophisticated techniques during the package creation.