If undershooting a track were a concern then the restriction would not be "max 185" it would be "exactly 185".
Flying the same track at 100 knots or 1000 knots still has you on the same track (though the G force at 1000 knots would be quite impressive), hence you are in the same position relative to terrain at either speed.
Aterpster, can you clarify why a speed restriction for terrain protection is necessary if the aircraft will be on the same track regardless of speed?