The developer will do the rollback with the blessing of majority of the forgers, it's basically a coordinated hard fork that is happening all the time in alt coins (and Bitcoin had one too).
Thinking about this longer I get more concerned. Let's say someone donates $5M worth of X to Israel/Hamas (just picking a random conflict that most would be familiar with which also has strong opinions in both camps). Someone creates a thread on the Xtalk forum slamming the injustice about giving so much money to such horrible people. The community generally agrees, namely the forgers, and they decide to roll back that transaction and give the money to the other side instead.
How many people are needed to effectively perpetrate a 51% attack on their own blockchain? Doesn't that defeat the purpose of an autonomous currency if a relatively small group of people (let's call them the coin's government) can make policy decisions based on political affiliation?
Maybe there's no way around this because someone(s) need to maintain the code so it'll never be completely hands off.