Wait.....WHAT?!

The Pink Bean Slayer Medal quest appeared to me after I got to that point in the Time Temple (it might have been that I used my first Marble of Chaos to actually enter the registry NPC room). When the patch first came out, I didn't have that quest in the list. But it appeared not long after, and I believe that was the trigger. Something triggered it, and it definitely wasn't defeating PB. I never attempted to kill it, either. Then I was able to "complete" it like the others.

I have it too:

 Spoiler

In short, I'm saying my theory is you only have to enter the registry room to make it appear. I don't know what else I could have done to trigger it.

Ditto to everything Felix said. I'd screenshot that I "have" the medal as well, but his is enough proof. I don't recall exactly when the quest became available, but I just remember it always being there every since the medal quest...then again I did all of the Time Temple quests the first 7 hours the patch was out, so I most likely triggered it before really talking to Dalair.