Steps to Reproduce:

1. Summon a baby turtle via command: /summon minecraft:turtle ~ ~ ~ {Age:-600}
2. Give turtle resistance V effect to avoid its death via command: /effect give @n[type=minecraft:turtle] minecraft:resistance infinite 4
3. Summon an ocelot via command: /summon ocelot
4. Keep feeding the turtle with seagrass to accelerate its growth until it grows up.
5. Replace ocelot with other (un)tamable mobs to compare the difference, such as wolf, cat, skeleton, etc.

Observed Results: Untamable mobs, such as ocelot and skeleton, keep attacking the turtle, while tamable mobs, such as wolf and cat, stop attacking the turtle.

Expected Results: All mobs should stop attacking the turtle.

Additional information: Although mobs behave differently in Bedrock Edition as well, it doesn't depend on whether its tamable. I'll try to figure it out and create a new ticket in MCPE.