> Apple leadership basically assumed Google would screw them over sooner or later if they could.

This should be the default assumption for any relationship - doubly so when corporations or big $$ is involved. That's why we have legal paperwork even for inter-family agreements - your Mom & Pop may love you now but in 20y when dementia sets it, that may be out the window (or Mom dies, Pop remarries and Step-Mom hates your guts, etc etc).