So are blocker bets officially dead on these forums?

I don't think blocker bets are dead. Again you bet 2/3 PSB on the turn, nothing about that is a blocker bet. You are risking far too much to find out where you are at. In this particular a it makes no sense to bet. If villan will bet 100% of the time checking is far better than betting. It has nothing to do with the sizing we might have to call down. It has to do with going with our read and making the best +EV play and betting as stated only gets worse hands to fold and better hands to call.

Making a 2/3rds size PSB so we don't have to call bigger bets on the turn will also create a very awkward river spot. What was your plan if you were called? The pot was 480 and we bet 320 and villan calls making the pot around 1100. Now what? Check call? Check fold? Bet another 2/3 blocker bet?

I'd like to just be clear that I don't hate a blocker bet of say 100-120 only if we can get value from worse. We also have to be certain we will never get bluff raised. Just a few too many ifs in this spot.

I agree that it was sized too large to be called a blocker bet.

In my experience, broadly speaking, blocking bets work very well at 1/2 and often not very well at 2/5. At 2/5 they are more often attacked as weakness unless you have a very solid winning image. YMMV