Earlier quoted context omitted.
You would be missing the key "the phone is, beyond doubt, yours" step.
I have been a juror on a criminal case that relied heavily on phone records. There was no fingerprint system involved, and yet it was clear beyond reasonable doubt that the phone belonged to the defendant. The phone company can testify that the phone corresponds to a given cell number. Other people can testify that they spoke to the defendant on that number. No one piece of evidence exists in a vacuum; all the pieces…
I'm not contending the "wasn't really yours" point. Phones get stolen, misplaced, left behind, etc. with enough frequency that "it's your phone and it registered/triangulated with this position" may be strong circumstantial evidence but still isn't proof. That it was used in a manner requiring your finger (still attached to your body) does.
Don't get me wrong, I'm with you on protecting the accused from compulsion to self-incrimination. Just observing that the fingerprint sensor, coupled with the enormous data being collected on/about the device, isn't helping 5th Amendment rights.