No, his script is handling it properly (based solely on this example).
Monotone uses UTC internally and git does some crazy wacky things with
timezones (in short, the timezone shown is /just/ for prettifying the date;
the timestamp by itself *must* be the time of the commit in UTC). See
https://kerneltrap.org/mailarchive/git/2007/2/6/237902
$ mtn automate certs d137c7046bae7e4a0144fee82bfce8061f61e3b3 | grep date
-A 1
name "date"
value "2000-03-23T03:09:51"
$ date -d "2000-03-23 03:09:51" -u
Thu Mar 23 03:09:51 UTC 2000
$ date -d "2000-03-23 03:09:51" -u +"%s"
953780991
Thanks for checking this.
Cheers,
Derek