My guess is that "There are no neutrons flying around" is a flippant way to say it's not ionizing radiation, since the common ionizing radiation is made up of alpha particles, beta particles (electrons), neutrons or very high frequency photons.
Imagine it says "It's not like there are high speed neutrons flying around".
Once again, it all depends on the frequency! Gamma radiation is EM radiation and can cause nuclear fission [1], which in turn can release neutron radiation.
I'm fairly certain that no iPhone model to date emits gamma radiation, though.
