Rollbacks do not currently count at all towards pushing a post to Community Wiki. This was tested way back in August 2010 and still holds true today. They certainly count as edits for the purpose of existing in the post's revision history, no matter how many you make, but for the intent of converting a post to Community Wiki, it is as if they never existed.
Revived the tests today just to confirm that nothing changed. And indeed, nothing changed. Thresholds still are the same, and the post remains completely unconverted no matter how many rollbacks happen.
As for whether or not they should, I'm fine with the status quo mostly from the perspective of "Don't need to fix what isn't broken" - it's been this way since the dawn of the system and there's been no widespread inclination to abuse it. Abusive use would thus be the outlier in the statistics and so that should be the "exception" that is handled by moderator intervention.
