> Yes 165 dB SPL seems like a lot
It is quite believable that a ribbon will work at such levels. Remember the reason a ribbon makes such low output is that it has small surface area and high mass. At normal levels, the ribbon motion is sub-microscopic. And the typical magnet structure is linear to about 3mm p-p, more before distortion gets gross. Even if ribbon-slap against damping silk limits the motion, it is likely to be up above 150dB SPL.
> wonder what they used as a source to test it.
Compression driver on a tuned pipe. JBL 2440 on a non-tuned pipe can make 148dB SPL steady-state, easily 10dB higher on bursts, and tuning the pipe can approach another 10dB. So the 165dB SPL rating, if really tested, may be a measurement limit and not the mike's true limit.
There are more exotic methods. The near-field of a large pistol is well over 150dB SPL. However calibration is a pain because a pistol does not have a linear level control like an amp/speaker rig. Some of the very small stiff condensers have overload levels well above 160dB SPL and could calibrate the near-field. Of course a pistol's air-blast may be harmful to a ribbon.
There is also the pistonophone. Take the spark plug out of an engine, jam your mike in the hole, and crank. Same idea (without fuel!) will give pressures as high as you want, up to the 190+dB SPL overload level of the air itself (sound waves ccan't make negative absolute pressure), and if the parts (piston size and stroke, chamber volume) are carefully measured you can compute the pressure to sub-dB accuracy. But only practical at low (not tooo low) frequency. And not directly applicable to velocity sensitive mikes like a ribbon (though I suspect it could be adapted).
Electrostatic actuation should also work on a ribbon. To be linear over that distance it may have to be push-pull, a trivial matter. Considering the large distance and the high diaphragm mass, it might take insane drive voltages to approach ribbon overload.
Most dynamics have overload levels well above 150dB SPL. The ribbon may have an edge because of poor mechanical efficiency, but we don't worry about overloading dynamics. (We may splatt the mike-amp input, but not the mike.)
Condensers have a naturally non-linear electrical transducer, and an underpowered head-amp, and this normally (for music-racket mikes) raises the THD to ugly numbers before any dynamic or ribbon would show any distress. Obviously good condensers can handle any sound field that we really meet in musical recording, at least with the pad to reduce transducer and head-amp (and board-input) levels to tolerable size.
