> Landing the plane because of something that could be interpreted as a bomb threat without waiting to be sure it was intended that way seems like a precaution on the far end of reasonable, but still reasonable.

To qualify even for the 'far end of reasonable', you'd have to divert the plane. Returning to origin, especially when the origin is not one of the 10 closest airports and is in a much more densely packed urban area (with a much more harrowing approach) than any of those 10 renders this entire incident totally unserious.

There are real actual safety concerns to address in aviation. This doesn't make the top 1,000 list. It's wasted effort in a world where economy of opportunity is significant.