Okay if somehow one can't figure out that night comes after day, then one can hopefully count and know that 12 comes after 1. 1AM is in the middle of the night so 11 hours later, 12AM would be noon. 12AM obviously doesn't come before 1AM, thus midnight is 12PM, because midnight is when one day rolls over to the next and you get morning (or before midday) again.
Except the most widespread definition is the other way around: 12am is midnight and 12pm is noon. As that source argues, 12:01 during the day is clearly after noon, so it must be pm.
In the end my point stands: You can argue both ways and it is confusing.
I think it would be weird going from 12am (ante meridiem = before noon) to 12:01pm (post meridiem = after noon), therefore 12pm must come right before 12:01pm, so 12pm is noon.