I have done a bit of digging and rolled back all the way to around 10 days ago on his timeline, and there is no such thing (might have been deleted), there’s also the possibility that it was something he said during their conversations about wearing the pin, in which case we will just have to take Robbie’s word at face value, sans a confirmation from MoH.
Regardless, I think both of them acted rather poorly here. Behaving like jilted lovers when clear headed, grown men would just talk it out, put a generic statement with some fluff detailing his departure and go on getting on.