[some1else]

It appears that the author was indeed not too closely familiar with the premise of the Y2K bug, as they mention the change "from 19 to 20"

... the Y2K Bug, and it prophesied that on January 1, 2000, computers the world over would be unable to process the thousandth-digit change from 19 to 20 as 1999 rolled into 2000 and would crash ...

That wouldn't be problematic, since the numbers don't loop around (like when going from 99 to 00).

[le-mark]

A lot of these systems stored the year as two digits. So 19 to 20 wasn’t the problem. The problem was mainframe based systems are/were almost entirely based on fixed length data representations; cobol copybooks, tape and dasd datasets (ie files). Expanding all those from two bytes to four was a lot of work and risk is some organizations.