[nvk]

I think they are being over cautious (other implementations are not as concern), but yes still in testing. There are over 100 nodes, doing a bunch of transactions no money lost.

[ActsJuvenile]

100 nodes for a network worth hundreds of Billions of dollars: that's not over cautious, that's under cautious.

[IncRnd]

Has there been a threat model performed by a security person (not a developer)?

Functional testing only goes so far and stops at the assumption that the code and design are correct.