Fair point. Another option is that the FBI knows more about the nature of the drones (size, lights, other identifiers, etc) either via visual identification or

Fair point. Another option is that the FBI knows more about the nature of the drones (size, lights, other identifiers, etc) either via visual identification or other sensors (classified, at related military installations nearby) sufficiently that they can be confident that there are no, say, explosives or guns attached and thus the drones are "safe". But they still don't know whose they are. Another option is a variation of the above, where they might have a "person or company of interest" that is too soon to talk about, but they suspect the game being played is that they are owned by some tech startup who is trying to fly their/others drones around to drum up business by scaring people to in turn secure huge military contracts for drone-sensing and drone-countermeasures which they can sell as a solution to the problem/risk they've created. Am I too cynical? Or as the original poster implied and some statements I've seen are clearer about than others, the wording is just sloppy in distinguishing between: "There is no evidence these drones are a threat/harmful" (ie they have been non-violent, so far) vs "There is not a threat here" (of any kind now or future... "keep calm and carry on"/"Don't panic... because we told you so; we don't see any particular reason".)