Don't apply to matters of national security. Seeing as solar winds supplied every branch of government and just about every company that matters in the U.S., I would imagine that there are a lot of people under gag orders, or prohibited from talking about classified Intel with people that don't have clearance. To be safe, it'd be wise to not have company officers who also hold clearances.
The statement about supposed CISA opsec guidelines is equally confusing, can you please cite the specific guidance you're referring to which would keep executives in the dark? I'm pretty familiar with the guidance CISA has issued and I don't believe any such advice has ever been given.
Before an executive would talk to the media about a subject like this, they would absolutely have gotten details from their internal security team.