He is referring to the EFP getting fired from distance while traveling in air at high speeds. That would be like flying at Mach 2 and trying to hit a plate at 100 meters with a pistol...
A SFF warhead is just a warhead like a HEAT warhead... the HEAT warhead of the HERMES or Vikhr have no problem hitting a target while flying faster than mach 2.
Moving at about 6km/s a SFF moves in a fairly straight line... ground based anti helicopter mines developed by the Soviets quite a few years ago can hit a helicopter in flight with a SFF warhead fired from the ground...
And as I said submunitions using a SFF warhead was developed in the late 1980s in the Soviet Union and deployed in the Late 1980s using MMW radar aiming.
UAV's like that would be easy targets for just about anything.
A MALE or HALE might be, but a micro UAV from 10 kms is neither an easy to see target or easy to track with IR or radar.
they ended up having to deploy MiG-29s against Georgian UAVs in the 8 8 8 conflict because standard MANPADs wouldn't lock on such high altitude small targets and it was above the effective range of 23mm cannon. SA-17 could kill them but was over kill.
maybe they developed the 2a46m5 back when they thought the T-95 was gonna be a thing- that monster was meant to serve as elite tank alongside more numerous T-90.
they aren't working in a vaccuum... the developments of the 152mm gun will be known to the workers working on the upgrades of the 125mm gun and technology developed for one that is a step forward would no doubt be added to the other in time.