  Oscillatory behavior of electron capture rates in the two-body decay of
hydrogen-like ions into recoil ions plus undetected neutrinos, with a period of
approximately 7 s, was reported in storage ring single-ion experiments at the
GSI Laboratory, Darmstadt. Ivanov and Kienle [PRL 103, 062502 (2009)] have
relegated this period to neutrino masses through neutrino mixing in the final
state. New arguments are given here against this interpretation, while
suggesting that these `GSI Oscillations' may be related to neutrino spin
precession in the static magnetic field of the storage ring. This scenario
requires a Dirac neutrino magnetic moment six times smaller than the Borexino
solar neutrino upper limit 0.54 x 10E(-10) of the Bohr magneton [PRL 101,
091302 (2008)], and its consequences are explored.
