but if you have two 60db transmitters, the max you can produce (from my understanding) with constructive interference is 70db , since db is logarithmic. so does that mean the transmitters in question were already transmitting at 100+db?

Some ultrasound devices operate at power levels that would be dangerous by themselves if they were at a different frequency. Eg the article mentions "One advertised jammer emits 120-dB ultrasonic interference at a distance of 1 meter".

2x 60dB is 63dB.

If the two sources are coherently phased up you can get 66 dB.

yeah sorry, got apparent loudness and amplitude confused.

While true, the energy delivered to the subject depends on the radiation pattern. A 100W light bulb can help you pick out clothes in the closet, a 100W laser can cut steel (sorta).

A 100W laser cuts acrylic and wood, not steel. This is the power level of hobbyist laser cutters.

That's in part why I said 'sorta', but Kern actually sells a 150w CO2 laser that they will support for metal cutting applications (2mm for mild steel).

I'll conveniently ignore the O2 assist for the sake of counterpoint. :)

Also tl;dr: They don't explain anything about how that can cause the observed symptoms.

Probably because it's possible for people to implement these sort of weapons, and they don't want terrible people inflicting somewhat untraceable brain damage on unsuspecting victims, seemingly out of the blue.

If they're leaving out explicit (or even the vaguest) details, it probably means that's the only thing keeping this out of the hands of weirdos.

Also, other layers of secrecy are likely in play. It's probably already known that such weapons do exactly these things, but how would people even know, without published research? Top secret military experiments? Private research performed by military contractors? (in other words, takes one to know one)