Sukrim, the actual implementation has more casuistic over what is described in the paper. This is the case for both Ripple and Stellar.
What makes you think that Ripple is not vulnerable to the consensus fault and subsequent reorganization that affected Stellar? (other than the fact that it has not happened yet)
Edit: Consider for relevant discussion, by the inventor of the protocol:
https://stellartalk.org/topic/6698-jeds-technical-explanation-of-the-ledger-fork/Here's the implementor of this protocol:
https://forum.ripple.com/viewtopic.php?f=1&t=8629&p=59073#p59073 ("I believe the Ripple protocol is immune to forking when properly implemented.") and
https://forum.ripple.com/viewtopic.php?f=1&t=8629&p=59222#p59222 ("The latest post from SDF reaffirms Ripple Labs' position that the Ripple consensus protocol has no known flaws. Their account suggests that Stellar’s fork resulted from an operational issue. We’re happy to review any further details they provide.")
To my knowledge, SDF hasn't even released ledger headers(!) that give proof that such a fork even happened by the way. I guess they really managed to screw up (as they apparently put code into stellard that would consider a consensus ahead of time). You're welcome to run your own simulations or give actual proof on what would ever cause a node to end up in any state that it considers global consensus to be reached while in fact it hasn't.
