Apple is the largest company in the world so no, their “indignation” over having a competitor is never justified.
You are also assuming that only Google benefited from that relationship which is wrong.
Google is a software and services company and in an iPhone world Apple would decide how and when these services are presented to users, if they are presented at all. That is an unacceptable amount of risk as Apple had a disproportionate amount of leverage in that arrangement.
Actually what Apple's (relative) size is should have no bearing on whether they have a right to be indignant by a breach of trust.
And I disagree with you about what the balance of power would have been in a hypothetical Apple-Google cooperative partnership. What were Apple's alternatives if Google were to withdraw as a backend services partner--perhaps a direct competitor in phones? That doesn't seem too palatable. Doing their own backend services? How's that working out for Apple today?
You are also assuming that only Google benefited from that relationship which is wrong.
Google is a software and services company and in an iPhone world Apple would decide how and when these services are presented to users, if they are presented at all. That is an unacceptable amount of risk as Apple had a disproportionate amount of leverage in that arrangement.