@pconwell This has happened to me twice in my own home within my own isolated network. Unfortunately the defaults are hard coded in /usr/local/emhttp/login.php. You could edit that file but it probably won't survive an update.
As a dirty workaround, I disabled this feature by changing the "/var/log/pwfail" folder into a file:
rm -r /var/log/pwfail
touch /var/log/pwfail
You could also create a cron job to delete the files in that folder but this way is simpler. The next time you enter your password incorrectly three times in a row you'll just see an error message saying it can't write to that folder and you won't be locked out of your own computer.
Of course if you're on a shared network think twice about doing this. Your computer, your choice.