I would hope all entities with nuclear capabilities have de facto safeguards in place to prevent anyone from actually launching a nuclear attack. Although, I would also hope they wouldn't talk about them as it diminishes the deterrent effect that is the only potentially good thing about such weapons. Nuclear weapons should never be used but people who can use them should not say that.
I read that comment as saying there are extra safeguards currently in place that go above and beyond the normal safeguards. If the existing safeguards for a normal president would be enough, Pelosi being third in line for the president likely wouldn't have to ask about them.
