I'm not sure that changes anything, but you can but try.
At the end of the day, your employer can (apparently) send you to any branch - we have established that.
However if this individual has the 'knowledge and experience' to work there presumably everyone on your grade has the same, so you could try and negotiate for you to have a 2-week stint - then by implication everyone in turn gets a go.
I have no idea what you do, or whether it is feasible, but it would better to try and negotiate a 'lesser pain' for yourself.
I would be inclined to not even mention that you know/suspect that the first individual fell out with the boss - just try and use the 2 weeks temporary transfer that happened before to your own advantage.