I seem to recall something along the lines of large bombers running valves as they were less prone to effects of EMP around nuclear blasts. Not sure if this perhaps something similar?
The majority of the on-board avionics were based on vacuum-tube technology, not solid-state electronics. Although they represented aging technology, vacuum tubes were more tolerant of temperature extremes, thereby removing the need for environmental controls in the avionics bays. With the use of vacuum tubes, the MiG-25P's original Smerch-A (Tornado, NATO reporting name "Foxfire") radar had enormous power – about 600 kilowatts. As with most Soviet aircraft, the MiG-25 was designed to be as robust as possible. The use of vacuum tubes also made the aircraft's systems resistant to an electromagnetic pulse, for example after a nuclear blast
Soviet gear was robust because robustness and repairability was priorities as a design criterion. It's not an automatic product of how they doled out work, or of their defense industry generally.
Not sure if this was a conscious decision wrt EMP, or was it just that they were in a hurry to develop a jet bomber for delivering nukes and they reused existing stuff as much as possible.
Flight engineer and radar operator in the seats behind would have got the fancy new (for the early 50s) electronic things.