score:3
It turns out that Office Depot Mexico is open on public holidays and their closest branch was only 8 minutes walk from my hostel.
I paid 10 pesos for use of a computer for 15 minutes (the minimum time) and then 8 more pesos to print out 7 or 8 pages.
In Mexico, Office Depot's open hours for most branches are:
Monday to Friday, from 8:00 am to 10.00 pm
Saturday and Sunday, from 9:00 am to 10:00 pm
There is a list of branches with different opening times on the company's FAQ page.