I'd recommend checking the agenda often while you're there as a lot of these sessions are rearranged on the fly and very popular sessions are often re-run on a different day, sometimes the presenters can't make it and have to cancel etc etc.
For further actions, you may consider blocking this person and/or reporting abuse
We're a place where coders share, stay up-to-date and grow their careers.
I'd recommend checking the agenda often while you're there as a lot of these sessions are rearranged on the fly and very popular sessions are often re-run on a different day, sometimes the presenters can't make it and have to cancel etc etc.