We have been over this 10,000,000 times on this site. In order to have a PR at a distance, you must line up and run that distance. Whatever is your best time is your PR. Nobody cares what ‘he could of’ done based on extrapolations, points, inference, or sheer speculation. According to IAAF, Jacob’s PR is 1:46. Until he runs faster, that’s what I’m going with.
The bigger question is as a 15/5 guy, will he step down to the 800 to satisfy your curiosity?