Drowned is being pacifist at day IF you dont attack him or if the place he is at is not too dark, Thats behavior only supposed to go to spiders.
If you dont get what I mean/Want Proof, watch the small video I made:

https://youtu.be/dXfmBoBOUaE

(At the final I show him being pacive at day and getting aggresive after its dark, The rest is just me showing how to reproduce. I was at creative when growing tree, but I changed to survival.)