Yes, that's very odd. Because without such corporate policy being allowed, competitors can easily bribe some employees to loudly speak it out and use it as evidence of bad acts/intention. It's almost impossible to counter it as long as they're careful enough to hide such collusion.
You're overreacting. Corporate should have a minimal defense against these kinds of attacks in the court. One defense is "Okay, we don't speak this in our company. We made it clear by policy and if someone does at least this is evidence that it's not our company-wide strategy". Of course, whether this claim is accepted or not is up to the court, but interpreting this as a part of evidence destruction is pretty "creative" and I see this as a signal of being a weak case.
