Very few serious scientists would claim that, considering that not even all planets have magnetic field. The Moon doesn't have one, for example.
But even if we assume that he only talks about planets with magnetic field, synchronization of flips between all of those planets would be nothing short of a miracle. And as you move farther from Earth the question of "the same time" becomes a relativistic problem.
The moon and mars don’t have magnetic fields at all but do have magnetic patches that are left over from when they were geologically active (they don’t move at all). Venus has a surprisingly weak magnetic field. Mercury wasn’t expected to have a magnetic field at all but does have a weak one. The gas planets all have strong magnetic fields.
None of the magnetic fields aside from earth have been studied in any kind of detail. Certainly not enough to declare that all the planets are behaving the same way.
To further complicate things is the fact that the sun’s magnetic field is really chaotic.
http://www.iki.rssi.ru/mirrors/stern/earthmag/planetmg.htm