That's incorrect. There's a call to action to register to submit an event here:
https://www.gp.org/earth_day_to_may_day_events_calendar
That's how the spam got in.
Edit: here, I made one for you: https://www.gp.org/janon/aaron695_hello
Edit2: it's deleted, looks like someone is finally doing cleanup
They did the same with a 'job ad' on the hosts web site -
https://webcache.googleusercontent.com/search?q=cache:2Uw0_n...
They did the same with a 'job ad' on the hosts web site -
https://webcache.googleusercontent.com/search?q=cache:2Uw0_n...