It was implied in the story that the husband was looking up how to create a pressure cooker bomb as well out of curiosity. Even that might not be enough thoug

It was implied in the story that the husband was looking up how to create a pressure cooker bomb as well out of curiosity. Even that might not be enough though. If FBI are smart they just classify each user into brackets of suspicious activity. The top N% get investigated, where N depends on the current available resource/budget. Not hard to believe at all.