Zoom is of course still a national security threat.
Calling nearly everything on or related to the internet a matter of "national security" is to demand that everything be overblown.
People can't be convinced it's used for child pornography, because that's pretty easy to prove/disprove. So now the boogeyman is national security.
Only those who have access to the underlying classified information can legitimately make the argument. Those who don't have the same access must trust those who do.
The system breaks down quickly when the former group gets everyone into a war because they failed to vet the underlying intelligence or purposefully misconstrued the intelligence or they just moved the goalposts of "national security" to include preemption.