Yes I'm not gonna defend Google's privacy issues, but privacy is totally different from security. People tend to confuse them. I understand it if it's average Joe got confused. But if you are a "security consultant" and you still have no idea what's the difference between them, then that's a big problem.
Regarding security, see examples like https://qz.com/1844937/hong-kongs-mass-arrests-give-police-a...
For privacy, I guess you can have full confident that Apple has the intention to keep your data private. But do you have full confident that Apple has the competence to fulfill that intention?
Google doesn't have the intention to keep all your data private, sure. They are an ads company after all. But for things they want to protect, in most cases they are competent enough to protect them.
(Disclaimer: I also worked for Google, but the "employer" I mentioned in my original comment was not Google)
Fortunately, it seems google has separated security updates from the OEM updates on some newer phones it seems. The phone I bought In November 2018, right now is receiving monthly security updates via Play Services updates, and is right now on the May version for some time.
Apple pioneered usable security with TouchID and the secure enclave; a lot of Android fingerprint readers were gimmicks for years, same with the face unlocks. https://manuals.info.apple.com/MANUALS/1000/MA1902/en_US/app...
They also invest piles of money into privacy https://apple.com/privacy (1 minute overview), https://apple.com/privacy/features (in-depth with links to whitepapers).
I imagine that's where your teacher was coming from.