Rated 4 out of 5 stars

It gets five stars if I can figure out how to launch it as a console command... i.e. seamonkey -addressbook for seamonkey address book. Then it could be binded as its own component like the other seamonkey/ice-ape components .

This review is for a previous version of the add-on (0.3.1). 

A workaround

You can use
seamonkey --chrome chrome://lightbird/content/sunbird/calendar.xul
for now. :)
The proper option will be -calendar, but it doesn't work yet.

Edit: Fixed for the next version.