I haven't thought through it enough, but it really depends on how one sees reality I would think. If you're in one timestream (thread) and I'm in a another, how does that effect our ability to influence things in a third timestream?
If I enter a timestream and stab the monk, then leave, what happens if you've entered the same timestream and turned the monk to ash?
Not sure if this could even be fun though for most, because you have to think about read-update-write operations...
Hm - so basically trying to think if there's a locking situation here? Or thrashing? Possible - I could see the Formians as a cause...