Well, I just assumed that Safe Mood would disable the persona. If it says "all extensions disabled", then that sounds like it would include everything, including personas. I was really surprised to find that it didn't do this. I wouldn''t know what to anticipate if the persona continues to run.
But now the Add-ons Manager has stopped showing the correct them in normal mode.
I created test profile FOOBAR with Persona Switcher and some personas and some full themes added. Selected Noia Moon theme with Happy Clouds persona. Restarted PM in Safe Mode. Happy Clouds persona persisted. Deleted Persona Switcher. Restarted and in Safe Mode dialog selected "Reset all user preferences to Pale Moon defaults".
Now PM is clearly using the default theme. However, the Add-ons Manager believes that the "active" theme is Noia Moon.