I don't see any reason why one can't occur 3 years later. Actually, over like a thousand years I think there is +correlation year-to-year of ENSO events (warm ENSO would favor at like 50.1% warm ENSO the following year). I think the Nina snapback that has been so strong this century is a bit of anomaly in the much longer term

Huh? The point is it had no “precedent” before (and has none since). Who knows how long the return period is for such an occurrence? We don’t know because we only have ~75 years of solid data, which is barely a snapshot in this context. Strong Niños occurring within 3 years of each other is easily within the limits of ocean-atmosphere physics. We know they’ve occurred 4 years apart, mere decades ago. Two events occurring 3 years apart would have a longer return period, yes. However, I’ll wager you it has occurred dozens of times over the last millennium.

EUG on pace for 15" of rain this month.

Using stats from almost 40 years ago kinda dilutes your point, though. There's been a lot more data since then.