According to the Google support site, all Pixels are encrypted by default. So, this shouldn't even be possible...unless perhaps there was no lock code on the device?
Of course Drive and Photos files are in Google servers and aren't E2E encrypted, but I don't think that's what you're talking about.
Full disclosure I work at Google but on nothing related to this.
[1] https://support.google.com/android/answer/7663172?hl=en
[2] https://www.techlicious.com/tip/what-to-do-if-you-forget-you...
The Twitter user most likely has an easy to guess password.
Sending a phone in for repair negates the shoulder-surf issue but yeah.
Perhaps Google just has a backdoor.