Yeah, in every field there are lots of cases where people end up saying this because professionals who should know better don't. Or cut corners because of resource constraints. Or, just screw up something they actually do know. Or...
They are just regular people. It's not a world of super spies. I am sure GRU is not that much different. Even the top folks eat corn flakes like everyone else.
People make mistakes all the time.
This might be bullshit but just saying so is hardly a compelling argument. I will wait for more evidence one way or another myself, with the obvious disclaimer that anything could be bullshit.