And yes, all studies have limitations, especially observational studies done in the middle of an emergency.
Here's your claim: "There was never any indication in the data that a previously recovered person posed any kind of heightened threat to anyone else"
That is quite obviously false.
If you believe there was superior data available at the time, please share it. Otherwise, yes that is exactly what the data showed (imperfect as all data is).
> Eventually things calmed down enough that studies could actually be published showing the efficacy of a prior infection without risking careers.
Like which studies? (Not that more recent studies could've possibly time-traveled to inform your decision-making in the past, of course).