That is close, but may not be sufficient. A big focus of such logic is hospital acquired conditions. Some bad events could happen on the day of admission that would not be considered POA. For example, if on their first hospital day a person had a fall, or a complication of a procedure (such as stroke), those would not be considered POA.
If it were easier to represent logic using datetime (e.g. for EHR data), that might help (e.g. detecting that an adverse event happened at least X minutes after admission). However, even that might be brittle, depending upon how robustly the EHR (or ETL) distinguishes between the time an event happened vs. when it was recorded.
By contrast, the medical coders and clinicians partner to determine what should truly be considered POA, regardless of when the conditions (and their start time) are documented. The coders ensure that the clinical notes document and justify the POA status, given their importance in quality & safety measures and associated payment or penalties.