[tedks]

The thing is that it takes a significant amount of time and bandwidth to get flagged as an exit and included on circuits. So your set of hosts is going to be pretty limited to start; most hosts are pretty hostile to Tor exits as it is, and are going to shut down an exit hosted in their IP space because they don't want to deal with the abuse complaints. In contrast, the exit scanner can be part of the first users of an exit node. You could try to detect the scanner, but the nature of Tor is that this isn't feasible.

In any case, you can solve the problem of distributing software over Tor by setting up a hidden service. The Tor devs have been making noise for a while about creating an "onion service" that isn't hidden, but has the same guarantees as a hidden service (an improved version of exit enclaving).