Is there any way of confirming this, one way or the other? Would it affect any of the star's 'observeables', so to speak?
I know that two similar questions are up on Stack Exchange-physics, and I asked a somewhat similar question about whether hydrogen atoms occasionally form short-lived neutrons...
The answers talk about how energetically unfavorable these events would be, but...
Even energetically unfavorable things sometimes happen, correct?
If the neutrons in a neutron star decayed on a 10 minute timescale, but were in equilibrium with the reverse process of neutronisation, then a neutrino-antineutrino pair would be emitted for each neutron decay.
Since the neutrinos can easily escape from the neutron star, because the neutrons are degenerate, each neutrino would take away $\sim k_BT$ of energy.
But the thermal energy content of a degenerate neutron gas is $\ll k_B T$ per neutron, so a neutron star would lose all its thermal energy on a timescale $\ll 10$ minutes.
We know this doesn't happen, since thermal emission can be detected from neutron stars hundreds of thousands of years after they were born (e.g. Sartore et al. 2018).
Instead, although there is a very short period (seconds) where very rapid neutrino cooling is possible, once a degenerate state is approached then further beta decay is almost blocked by degenerate electron and proton gases formed as decay products and the cooling becomes much slower. See https://physics.stackexchange.com/a/105475/123208
