I don’t agree as we see what has happened with the lack of action regarding the North Korea and Iran nuclear programs.
No one will act until something goes bang.
A group like A-Q does not have the assets to protect something like a nuke, compared to what Korea has, or the US. They also don’t have good access to “national technical means” so that they really can’t be sure of how well the operation is hidden.
If they had a well-defended bunker with good security inside and out, it would be pretty visible in a number of ways. Taking it out would also be visible and hard for a nation to deny.
If they have it stashed in an old warehouse on the edge of town with a lookout up the street, it’s pretty vulnerable and it could be taken down without a lot of fuss for a country, and fairly easy to deny.